7.1 vs7.1.5

What is the difference? does anyone know?

What do you mean? 7.1.5 is the latest version in the 7.1 branch (and overall). It only contains an important security fix, so it's recommended to be on it.

Short answer:  A lot

Long answer:

Dolphin 7.1.1

Enhancements: 

- jQuery, jQuery-UI, jQuery-Datetime, jQuery-Form, jQuery-Masonry, HTMLPurifier updated to the latest versions (#3057)

- Language corrections, especially in Russian language (#3029)

- Improvements in Facebook module for mobile login/join support (#3023)

- New photo popup for image view in Blogs (#3017)

- Video/sound file length is now updated for HTML5 player as well (#3031)

- "Show modules permissions" added to permissions page in Host Tools (#3019)

- "Share URL" functionality was added to Blogs, Ads, News and Articles (#3004, #3010)

- "Related Files" block for Photos, Videos and Sounds (#3042)

- Site sitemap now supports manually created pages in page builder (#3041)

- Speed and memory optimisation in site sitemap generation (#3056)

- Long text in site stats block fits nicely now (#3009)

- Info and error icons in forms now support touch events  (#3021)

- Comments actions are now tracking by counts in membership levels (#3026)

- Stricter checking for CGI mode in Host Tools audit (#3039)

- Subscribers are now automatically transferred to the new topic created by Autopilot in Forum (#3040)

- Annoying "Are you sure?" message was removed when user tried to navigate from sent message (#3045)

- Absolute URLS are now used in TinyMCE (#3061)

- Permalinks for some URLs were added to Blogs and Ads (#3055, #3062)

- More info for Timeline event when user posts on another user's timeline (#3025)

- Disallow browsing under "compatibility mode" in IE (#3071)

- New optional flag to not send mail in setMembership method (#3066)

- New developer Alerts for buildable pages (#3011)

- Improved IP detection in votings (#3074)

Bugfixes:

- date field problem in new Chrome 24 and Firefox 19 (#2955)

- profile field of checkbox type wasn't searchable (#3003)

- wrong sounds count in album (#3001)

- avatar was incorrect sometimes when profile photos was used for avatars (#2996)

- number of items in previously rated block wasn't changeable (#2940)

- video comment wasn't counted properly and wasn't shown in spy activity (#3022)

- files manual order wasn't applied everywhere (#3034)

- video upload failed when file name had apostrophe (#3046)

- wrong links to media items for approval in admin stats block (#3063)

- "Set as avatar" button left after Avatar module deletion (#3072)

- profile timeline slider could stop working in particular situation (#3024)

- admin can't access private albums (#3080)

- page wasn't automatically reloaded after upload finished and files are saved (#3081)

- forum Autopilot failed when topic title had apostrophe (#3040)

- changing default language didn't affect forum (#3051)

- banners with CDATA could brake forum (#3070)

- creating new group problem (#3078)

- missing pagination was added for some pages in Blogs (#3013, #3020)

- default privacy values was not applied for Blogs and Ads (#3049)

- manually approved Blogs had category and tags improperly updated (#3059) 

- map wasn't loading in map edit page (#3075)

- server side geocoding wasn't working in World Map (#3082)

- wrong box padding in message view (#3016)

- search for members in admin panel wasn't working when admin hits "Enter" button (#3044)

- sometimes it was wrong friend requests number in member menu (#3048)

- empty comment was left in Timeline after associated entry deletion (#3050)

- some data was left in subscriptions after member deletion (#3065)

- profile submenu was working incorrectly sometimes (#3067)

- manage fans button in Groups wasn't working in IE (#3068)

- some missing translations was added along with fixed typos (#3002, #3007, #3014, #3015, #3028)

- incorrect next page URL in notification page (#3073)

- design bugs in FF browser (#3077)

- warning message in Spy module (#3079)

Dolphin 7.1.2

Enhancements:

Social share and recommend functionality is now shown for public content only

More informative error messages in Facebook connect module

Profile's media album is now always selectable in upload popup for Photos, Videos, Sounds and Files modules

Autoplay is now supported in HTML5 Player module

eAccellerator cache support was removed (it always confuses everyone) since it does't support cache for long time

Automatic re-login during password change

Forum feeds for Events, Groups and Store modules

Description is now optional for Photos, Videos, Sounds and Files

Local links now open in the same window in RSS feeds

Forum now uses standard rich editor initialization

Some attempt to automatically stop bots to join the site

Some jQuery libraries was updated to the latest versions

Enhancements for developers: 

New alerts in admin side:

    system - admin_db_backup_actions

    system - admin_db_backup_page

    system - admin_modules_actions

    system - admin_modules_page

    system - admin_templates_actions

    system - admin_templates_tabs

    system - admin_templates_blocks_add

    system - admin_menu

    system - admin_modules_buttons

    system - admin_modules_buttons

New injections in admin side, similar to injection is user side

New parameter for timeline/outline service method to filter data by module

Bugfixes:

#3098 Wrong encoding in some files was fixes

#3089 Members count in admin side was incorrect sometimes

#3101 Comment posting characters count didn't work sometimes

#3110 Checkboxes didn't work correctly in mailbox

#3113 Hardcoded bold style in mainmenu was removed

#3114 Nickname field was removed from profile edit page by default

#3116 Subscript didn't work in profile popup action

#3117 Popups windows overlapped, when one popup is called from another

#3118 Curl timeout was decreased

#3119 Profile info page could display incorrect data in submenu

#3130 External JS/CSS files wasn't loaded from HTTPS URL for secured sites

#3132 Typos

#3166 Missing translations

#3133 Categories and tags with spaced didn't display associated data

#3142 PHP Warnings in list_pop.php file could appear sometimes

#3150 Template files was incorrectly generated on particular server environment

#3152 Custom language wasn't applied in time picker control

#3158 New user notify for admin didn't work

#3159 CSS/JS cache could become broken sometimes

#3172 IE9 could crash on the form with non-latin characters

#3084 Profile Customizer: controls in themes block in admin panel didn't work

#3087 World Maps: location wasn't updated when user edited location related fields

#3088 Media modules: upload failed when url is restricted in Page Access Module

#3106 Media modules: double slash in album links

#3120 Media modules: flash embed code did't work locally

#3168 Media modules: admin couldn't play non-approved files

#3169 Media modules: tags cloud on module homepage didn't have limit of displayed tags

#3090 Forum: posts from private forum were visible in live tracker

#3091 Groups: many fans weren't manageable

#3092 Groups: fans actions didn't work when permalinks are off

#3093 Groups: broken paginate in fans block

#3095 Chat: apostrophes in name broke chat

#3097 ZIP search: google maps based geocoding didn't work

#3099 Timeline: content from non-active members was shown

#3121 Timeline: media posted to timeline wasn't viewable because of privacy

#3100 Facebook Connect: redirection to profile edit page didn't work

#3128 Payment: incorrect user info was displayed in history after user deletion

#3143 Payment: some associated content was left after profile deletetion

#3155 Flash: some unused files were deleted

#3167 Flash: old info in Chat and IM help section was removed

#3161 Avatar: set avatar didn't work sometimes

#3181 Avatar: non translated image title could appear

#3171 Blogs: membership checking in post view in mobile app was incorrect

#3174 Articles/News: 'page not found' wasn't shown for non-existing entries

Dolphin 7.1.3

Enhancements

Antispam: delete user as spammer with all its content + reporting to central database

Antispam: add "nofollow" attribute for external links in user's content

Antispam: adding new DNSBL servers

Antispam: StopForumSpam integration

3rd-party libraries were updated

System language now changes language in Flash

Profile customiser: option to publish themes to public and to "my themes" for admin

Videos: smart video thumb generation to avoid whole black or whole white images

HTML5 Player: display poster for video

Allow to remove NickName from join form

Bugfixes:

#3177 Payment module - PDT mode

#3179 Photo upload followed by "close", appears in album but not in Spy/Timeline

#3185 Photos/Files: upload to non-latin album/folder could fail

#3186 Outline/Sounds: Link to Comments Broken

#3189 Photos: hidden photo displayed in spy

#3190 Email Templates: Space Between Text and Exclamation Point in Profile Activation Message

#3191 Comments: upon user delete, trigger tables aren't updated

#3193 HTML5 player: autoplay is always ON

#3199 Forum: bury/report of posts with "likes" shows "vote error"

#3203 Youtube videos problems

#3209 Wall/Timeline - Photo/Sound/Video uploading problem

#3211 Photo Upload problem.

#3215 Image is partially visible if column width reduced

#3219 Comments: incorrect chars length check for multiple lines without rich editor

#3220 Flash: sounds recording is not working

#3221 World map: make "disable dragging" option to work

Dolphin 7.1.4

   Enhancements

Automatic updates for 3rd-party modules (instructions for developers)

Better downloading for videos and sounds

Video upload for Mobile Apps v.1.8

     Bug-fixes:

#2684 Errors when switching upload value in photos IE8

#3134 Forum feeds in Groups/Events/Store

#3196 Russian Language

#3223 Subscriptions data isn't deleted from table 'sys_sbs_entries' if content is deleted

#3224 Videos upload on IE9

#3226 Forum: backslash issue

#3227 Forum: post reply when user is not logged in - causes JS error

#3233 Sounds aren't playing when flash player is used

#3234 member menu is not updated in realtime

#3238 Photos: embed photo link isn't working

#3240 Member Menu: Some Add New item text is all lowercase

#3241 Blogs: database error

#3242 Restrict purchase on Unapproved members

#3245 Forum: no topic info is passed when topic is deleted

#3248 HTML5 Player: Audio/video on profiles keeps playing after switching item

#3251 Problems with module's automatic update script.

#3257 Default profiles sorting for search results

#3258 Correct permission for sitemap generated files

#3259 View Profile and View My Profile submenu issues.

#3260 Photos: "Deactivate" button in admin's pending media

#3261 Photos: don't duplicate filename in description field

#3262 Sometimes date is not parsed correctly in RSS feeds

Or it's easier to read the Blog which gives you the low down on all versions of all products ;)

http://www.boonex.com/notes

Thanks guys for all your help I will be updating asap!