Except the escape in the vents in Aliens = Dallas in the vents. Also, surely the chestbursters would be equivalent -- Alien's scene ends immediately after, Aliens continues into a much broader piece.
What's the equivalent of Ripley going back to the hive?
Interestingly there are only about six major sequences and one minor-but-important sequence in either involving the Alien -- hugger, burster, Brett, Dallas, Parker/Lambert, air-lock at the end, Ripley in the shuttle; derelict, hive attack, sentry guns, operations/vents, Newt, Ripley in the hive and Ripley vs. Queen. But to say that they have the same amount of action is like saying Aliens has the same amount of action as a movie with just two people talking, but seven times one of the characters stands up and sits back down.