Do you think that with each Predator and AVP movie they show to much off, instead of a little to keep mystery and to save some ideas for a possible predator 3?
In predator 1 we saw the predator and some of its weapons and gizmos.
Predator 2 we saw more new weapons and technology, we learnt there is clans and a culture, there a re certain rules and so on.
AVP we learn that they have man hood rituals, they scar themselves to show that they have killed a very hard opponent, the embraced human construction, they used us as slaves, they have a mother ship.
AVP-R Predator home world, new weapons, more markings, and obviously more things to come.
with the alien films it was different.
AVP Predalien chest burster.
AVP-R Predalien (queen possible) rumoured new life stage
Alien we saw Space jockey, alien egg, face hugger, chest burster, warrior alien, egg morph in small nest.
In aliens we had Queen alien and more hive stuff.
Alien 3 give us the fact that aliens can be different depending on what the host is and a queen chestburster.
Alien resurrection gave use the forgettable viper pit and the newborn (but that doesn't count because its a one of)
There is still ore to be done with alien i.e. were they come from, space jockeys, new stages and so on.