What's more effective, a movie sequel or a part 2?

If you watched a movie at the cinema and you enjoyed it, more than likely you would be prepared to see the sequel. What if it was a Part 1 or Part 2 kind of story?

What is the difference between the two? Well a movie sequel is an entirely new outing based on the continuation of the previous story. Part 2 is more of a add-on to the last half of a previous movie, but can also be categorized as a sequel.

Why do we mix the two? Is there a marketing ploy behind the wording of Parts and sequels. What about prequels, or 'Recalls'?

As the sequels business booms, audiences are now almost geared up to accept the part 2 is coming, but to add a hook onto the end of the first movie is not always easy. If you don't plan a sequel then redrawing the road map, maybe years later, doesn't work so well.

Terminator 3 or Die Hard 4 are two very disappointing sequels that took place far apart and in alternate 'universes' of time from their predecessors.

Would you go to the cinema in 10 years time to watch a remake of the original 'Pirates Of The Caribbean' starring Nicolas Cage instead of Johnny Depp? (although by then, Nic Cage, would be too old)