on the iPhone
go to settings
usage
storage ( not iCloud )
manage storage
it will break down all our storage and tell you specifcally where your memory is going. , by category , like videos, and even apps like GTA III, RAGE HD, Pirates atc.
from here you can click on each app and see how much documents and data the app is using.
what does itunes say? does it say you have a lot of "other"
a possibility is that your iPhone already dowloaded your iOS installer and its sitting on your phone waiting for you to upgrade it
some people get confused about the storage that itunes reports. sometimes it shows you how much you actually have on your phone, but also what confuses people is it will say what your storage WILL be the next time you click on SYNC or APPLY
like ill click on my itunes and it will say i only have 500 megabytes left! but if i uncheck music, the free space goes up, indicating that the status bar reflects what your storage will be when you click on sync
storage available on the iPhone is how much space you have left.
storage available on itunes, can be different depending on what you are telling it to sync.
what bugs me is theres this problem in iTunes match, and its not widely known, and itunes match says if you turn it on , it will replace your music collection, and it does no such thing, and it throws your entire music library in "other' sometimes 20-30 or 50 gigs are wasted. and people have no idea that iTunes match is at fault,
so they go through all the hassle of restoring their iPhones, when all they had to do was turn off itunes match and delete the music library manually, and enable it again