discrepancy between phone memory and storage memory

[jackpower]

I have an issue, when I check app's phone memory space under the app menu, it says after calculating that I have 170mb free, so then I try to update or install new app and I get the message saying insufficient space check storage, so I do. Storage under phone memory is 98mb even after calculation. I know this wrong as I have uninstalled app's to free up phone memory n yes the app's were stored under phone. So what is going on, why the discrepancy? And how do I fix it? I have nothing else saved under phone memory except app's that I can't move to internal memory. Also why I'm at it, when updating app's, the update will be 30mb let's say but I only download 15mb it stops by itself, I realize that is all that's needed, so what does this mean in terms of space?is it really making room for 30mb but only installing 15mb cause that's all the app requires?

[Uliwooly]

@jackpower

You need a lot more free memory to be able to update and/or install apps, usually 500MB, what you could do is settings > memory > clear cache > check again. 

[jackpower]

Um theres no memory under setting, its either storage or apps, under storage I can clear internal memory but that's no help. Is clear cache under app menu, I can do this for each app I'm running but that doesn't free up more phone memory. I know if it around 100mb of free space I need to clear or uninstall an app to make room for new one. 170mb should be enough room for a 30mb app or update

[Uliwooly]

@jackpower

I had other Xperias with limited internal storage and if I'm under 500MB I can't update nor install any app, even if the app its few MB. 

[jackpower]

But app space is different to storage space even though they are the same but under different menus, app will say 170mb free while storage phone memory will say 98mb free

[Uliwooly]

@jackpower

Indeed, you have the Xperia J, so it will be 

settings > storage > Device memory > total space (this is for apps) 

Internal storage, this will be for music, videos, pictures. 

[jackpower]

Yep, I save all music, pics etc to 32gb sd card, I can only clear internal memory, I can't clear phone memory cache.
I really want to know why one area tells me something n the other tell me something different, they are both phone memory but under different menus n what can I do to rectify so they both read the same

[Uliwooly · Accepted solution]

@jackpower

That's how its supposed to work, the internal memory its partitioned.