Ohk, so there is WAY to much to read on this thread, so if this has already been said then my bad.
IMO, there are two major differences between the two trilogies. 1)Star Wars tells a story worth telling. Now it is true both series ripped off previous works of literature (Twilight obv. is Pride and Prejudice and Star Wars was based on a mix of Japanese Samurai books) Star Wars was the only one that ripped it off well. If you tear apart Twilight you will see P & P underneath, Stephanie whatshername did a horrendous job of hiding the similarities (if you`re so desperate to see an undead love story, wait for Pride and Predjudice Zombies to come out, at least they don`t hide what they ripped off). If you do the same with Star Wars movies, you will see some similarities, but George Lucas changed enough of the story to make it original. 2)Star Wars has staying power. Now i don't know about you guys, but I will definitely NOT be telling my kids about Twilight (the books or the movies). I will only bring it up as an example of how gulible our population is. Star Wars on the other hand, I will tell them about and I will show them the movies becasue it has a them and morals that cross generations. Twilight is just cashing in on a fad that I hope passes really REALLY soon.