Giger's is more biomechanical, but I can't fault ADI. They tried to get the "freight train meets a jaguar" look Fincher wanted and to stay true to Giger's artwork for the Alien. I don't even feel the two are really comparable. One is with the intent of making a dog-hosted Alien. The other seems to be Giger focusing on ways to make "Original Alien, take 2."