AFAIK, different OEMs just change the system's look and feel (desktop, launcher, keyboards, maybe some built-in apps that are usually crap/adware/spyware), not

AFAIK, different OEMs just change the system's look and feel (desktop, launcher, keyboards, maybe some built-in apps that are usually crap/adware/spyware), not the UI of the actual applications (e.g. GMail).