Kinda like that yeah.
Basically, we have 9 different enemy classes:
Large Walking
Small Walking
Large Flying
Small Flying
Ceiling Clingers
Stationary Floor
Stationary Flying
Crazy/Leaping
Wall Crawlers
Each class in the game has only one enemy type right now, so, any time you would see, for example, a Small Flying enemy in any region, it's going to be a bat. When we get all the enemies put into the game, you will only see those bats in a few regions, and other types of Small Flying in other regions.
I don't know if all regions have a theme, but some certainly do.