I think what you are seeing is the different factions, there are a whole bunch of different races, Vanguard (Humans), Dvar (Space Dwarves), Kir'Ko (Sentient Bugs), and others all with different looks and game mechanics.
Just a bit of a word of warning. I have tried the game out this morning and did find a major bug that if you want to customize your commander, it hangs, spinning beachball, requiring a force quit. So yeah there are some bugs.
Maybe they should have had a beta for Mac users before they released it so that they caught some of these bugs?
It's been reported in the bug section and I've added my voice to that thread on Steam, hopefully they'll get a fix out.
So anyone interested in the game, you may want to wait a bit until they fix that.