Different Unit System than Supremacy1914?

After playing around, invading, annexing, occupying provinces y'know the same old same old stuff. And this has been going on my head for days, does the Combat or Unit system work....

Like in Supremacy1914.

1 - 1000 Soldiers

Or are CoW Brigades more extended so if its just "1" then its just one Brigade with like 3.500 or 5.500 Troops in one Brigade Unit?

Cause Sometimes I invade a Province, and it has one brigade defending and Casualty Levels can go over 1000.