Alien vs Predator: The Last of His Clan

Rocks vs Acid
On the Japanese version's last stage, blocks drop from the ceiling forming new ground once they reach the floor (like in Castlevania 3). In the USA version they were changed to drops of acid and they do not form new ground.

New Chamber
In the Japanese version all you had to do is go forward to face the last boss. In the USA version, you need to bomb the ground and drop to another chamber to face the last boss, as shown on the map.

Last Boss Differences
To defeat the last boss in the Japanese version, you have to hit his arm until half of it falls off, and then you proceed to hit the other arm section until you defeat him. In the USA version, once the arm falls off, it falls off completely, and then you have to hit the Alien's body to defeat it.

Ending Differences
The ending was cut on the USA release, instead, it just says "Mission Completed".