As a biologisy, i think cameron did a perfect job, he gave the aliens a interesting and realistic lifecycle, he turn them into a social species.
Of course aliens died vs colonial marines, they had weapons, apc, the droship.. And they destroy all of these, they found another way to enter, during the whole movie they suggest they are smart creatures, the feeling is that even with weapons, they got theyr ass kicked.
The queen even comunicates with ripley, he let her go..
So no, of course big chap looked diferent, he was facing space truckers with no armours, experience or tactics and a cat, aliens faced a group of experienced and well trained marines with explosive bullets..