Free Space Different from iPad and iTunes

That has been an ongoing issue for awhile now. Problem is that the amount the device states is the one that counts, since if it declares itself full, no matter what iTunes may say it won't allow anymore in. A few ideas:

• In Settings / General / Usage / Manage Storage (under Storage), a list will build up with all the installed non-default apps, sorted by the amount of storage each and its associated settings and documents consume. If it comes to that, you can make an informed decision of which app will release most space.
• If you have taken and handled many pictures, try setting the date on the device at least to before you started using it for that, then check in the Recently Deleted album. It seems that the system can get confused and unlist old pictures instead of deleting them. They're still there taking up space, but you can't see them.
• And, of course, the traditional Force-Restart. Hold down Home & Sleep until the screen goes dark and an Apple logo pops up. Release and allow it to finish restarting. This is like a Windows Ctrl-Alt-Del. Doesn't erase or affect the contents, but can reset many internal counters and cure some odd glitches.

On top of those suggestions listed above I would also make a backup to the computer, then attempt to sync to the computer. I've seen the sync process help those files that are "deleted" but still listed as using memory. If the sync doesn't help try a reset to factory setting and then restore from a backup.

Also, before you do all this, make sure you have all your contacts backed up as well as saving all your photos directly to the computer outside of the iTunes backup. Game high scores suck to lose as well as rambling iMessages between you and family/friends, but most people regret losing photos. And if you do have text messages you want to save there are apps out there that can extract those messages without having to jailbreak your device.

If the problem persists after a reset/restore it could be a corruption in the OS, which would also copy over into the backup.

If you have to start over add apps slowly, because sometimes apps can cause problems and you might be able to figure out which one it is. Facebook was notorious for a while for causing problems, as well as those slot games, and some of the kids games.