Difference between drive, file manager, and downloads on my android phone? I know that Google photos access my pictures, no matter what device I get on, as long as I enter my email address. But, my question is that, what's the difference between drive, file manager and downloads app on  android phone?
With Drive you can view and manage files stored on your Google account. Those files are also accessible on Google Drive website.

File manager lets you browse your phone's internal storage, SD card and USB OTG storage, if supported by your device.

Downloads app only shows files inside default downloads directory (which is usually called Downloads and is placed in your default storage). So you can access files you have downloaded earlier using both Downloads and File manager.