Sorry Dart, I don't think I'm the best person to answer that question - I actually never played around with any of them, been sticking to the plain boring generic/default classes. From my shallow understanding, yes, each archetypes can be significantly different. I will jump on the game tomorrow and will take some screenshots for you of some of the archetypes.
Also, here is the post of Kingmaker information some kind soul has been updating regularly. It's got the list of available archetypes and prestige classes as well.
https://owlcatgames.com/forums/showthread.php?19-Information-known-about-the-game-so-far