iPhone free space not showing correctly

I have iphone6 128 gb iOS 8.4 and MBPr 15 inch with pressure sensitive touchpad OSx 10.10.5

when i lookup on my iPhone's usage section it shows 55gb free space but when i connect to iTunes it shows only 32gb free space

when i sync Photos from my mac it will increase same amount of storage in photos as well as in others storage.

i think it only shows in iTunes but in actual usage on iPhone remains same

is there any solution for this?

i tried to remove iTunes from my Mac but i can't.

please give me some solution.

I did factory restore my iPhone for this problem but it remained same

Thanks