First off, the oil that was spilled in the gulf was a lot lighter, but more importantly the waters are a lot warmer, and there is a lot more movement and dispersement. Remember, the oil eventually breaks down. Higher temperatures played a huge part in that. I have a few friends who are environmentalist that worked on the both spills, and all along they said the BP spill would be gone in a few months. I have heard that if you pick up a few rocks in Alaska, you can still find tar balls.