The Imperial Army and Imperial Navy aren't entirely separated. This comes through Moffs: Moffs are military commanders who command Navy and Army units. They are above Generals and Admirals.
So Navy and Army don't seem to exist as seperate branches of the military. Only as classification of different types of troops.
(Source: SWTOR Encyclopedia)
This was what I was looking for, thanks man.
I had known that they become separate branches somewhere between the Clone Wars and the last movies, but was unsure when the change exactly took place.