8 years ago
The xenos from Alien and Aliens are quite akin in style, and i still think the difference in the domes look is based on the Aliens' xenomorphs beeing older and more mature. I'd call them "one family".
About the xenos from the other movies - the Alien³ creature doesen't count, it's wasn't even born out of a human, and maybe even not from a "normal" facehugger if this "queen facehugger" theory is right.
The beasts from Alien 4 were different too, not because of their hosts but because they descended from a queen contaminated with human DNA due to the cloning process.
And the xenos from AvP 1... well, i heard a rumour that they've been genetically modified too, by the yautja, which could explain their absurdly short evolving time from embryo to fully-grown xenomorph. Sure, the preds don't want to wait too long for their prey to be ready for the hunt. Anyway, if that's true, the aliens from AvP 1 aren't original aliens too.
And about AvP2... yeah well i'm just preteding this movie never happened, my amusement for spinning theories to explain inconsistency errors ends there.