The reason I am not includeing non humans is cause if I did the answer would jsut be preds. Now feel to describe the diffrences of them in CM vs aliens.
I rank it like this.
WY- An autocratic mega corporation that regularly commits worker abuse and experimentation on innocents. Using the isolation of space they are able to keep thousands of workers in corporate towns with near total control over their lives. Although not fleshed out very well in CM the aliens lore gives us a good picture of what they like. Unlike the other factions the only motivating factor for their evil acts is greed. At no point does anyone benefit from their actions apart from a highly indirect increase in product availability. The only real benefit they give is the development of new tech but ummmmm everyone does so it kind of does not count.
UPP- They are just the USSR in space. But what sets them apart from WY is that they are based on principles. Sure they will control your life and kill you for stepping out of line. But these principles that motivate them can also lead to good things. These good things often come at a cost. Sure they saved your colony from xenos but now you have to suffer under their rule. Even if their idea of a post capitalist society has mostly lead to a worse life they are at least trying to help people. Sometimes they actually do.
UA- In aliens itâs just america in space. Most of you are from america so you know what thatâs like. Although just as brutal as the UPP at least half the time they wonât kill or oppress you with force. But they have committed so many war crimes so much they caused the CLF. Plus WY have turned them in a borderline corporate state. But thatâs more WY fault.
CLF- Since not much has been said about what they believe. Although we do have some info on the CM wiki. It seems they removed the part about a mostly peaceful worker revolt and the US bombing civilians. Again we have no info on why they are even fighting so for all we could know it was totally justified. Considering how marines act in game I can see it.