You kidding me? The difference with Pirates is that it has a ton of kinetic energy. The AAs may not be advanced, but there is stuff moving all around everywhere. Pirates being chased, cannon balls exploding, fire, water, people being dunked in wells, donkeys singing, pirates goofing around with explosives. The whole thing feels very alive, even if technologically it's not very advanced. There's also just a ton of amazing environments that you journey through -- from the caves to the great big reveal of the Wicked wench.
GMR offered almost none of that. It literally felt like you were walking through static sets and mannequins for 90% of it.