Google Drive has taken over my internal memory OK so I decided to migrate all my pics (10gb+) from Dropbox to Google Drive. Everything went as planned but surprisingly after installing the Drive app from the Play Store, it synced all my 10gb data back onto my internal memory 

Forgive my "noobness" but isn't the whole point of cloud storage the avoidance of such nuisance? How do I get back my internal memory without losing my data on Google Drive 

Thanks in advance.
Logically, from what I know about Drive, all items that are marked appropriately will automatically sync to all devices where Drive is installed (to provide offline access).

I don't personally use Drive often at the moment, but I believe there is both a switch for offline access while viewing detailed file info, as well as a star feature, that both function to show which items are set to sync to all devices (there's been a few updates since I used Drive often).

You might have accidentally checked a setting that told Drive to mark all those uploaded items as favorites/offline accessible files, while uploading.

I've never personally added so many files to a current versions of Drive, web or app. So, I'd have to compete a test of the activity with some test files and follow directions based on what exactly you did to identify, with certainty, what happened.

And in order to correct the issue, regardless of the cause, it may be easier to use one interface rather than another. For instance, Drive via webpage/PC may allow you to select all folders and mark all internal contents as not available offline in one click, but the app may not. 

I'm not sure which would be more efficient for such a purpose, I just wanted to suggest that it may be worth experimenting. 

And there's always the possibility that it is just because of a glitch in drive.