Lego Star Wars returned with the original trilogy in 2006 after an enormous success of the first Lego game based on Star Wars prequels. It utilized the same gameplay mechanics as the first installment, so you didn’t need to learn any new tricks.
This time you could play as Luke Skywalker or Princess Leia. Also, all characters could use Lego blocks to solve the puzzles, unlike the first game, where only Jedi could use the parts with the help of the force.
There were a lot more vehicle-based levels than before as well. But other than that you wouldn't be able to find any differences -- it was the same high-quality gaming experience.