I agree with the action v. talk thing.
Star Wars is basically a war movie set in space; whereas Star Trek is just plain... set in space.
Actually, it's kinda like LOTR set in space.
Oh, and to go all scholarly on you guys- Star Wars follows(almost exactly) the
Hero's Journey, and contains several archetypes that can be found in practically any fantasy adventure story, from the Odyssey to the Little Mermaid to LOTR. George Lucas actually started imagining Star Wars after studying the Hero's Journey(I'm pretty sure in regards to Sociology) in a book by Jospeh Campbell.
Infact, you can interchange the names of Luke Skywalker and Harry Potter in a basic plot summary and they're the exact same story =)
>> see it
here
That's why Star Wars is so popular- it's because it's a monomyth. It follows the same plot as hundreds of other stories.
Star Trek, on the other hand, while containing elements of the hero's Journey and also some basic archetypes(eg. Spock, Data, Tuvok are all the same), is
way more extensive and complicated. Atleast when speaking in context of all the series & movies, it is. TOS by itself is still very detailed, though. Its heroes, archetypes, and plotlines are varied, which doesn't register with most people. Star Wars appeals to a wider audience because of its universiality.
In continuing that point- SW focuses on the Force(and its immediate themes), while ST explores a bunch of different issues(death, suicide, relationships, invasion of privacy to name a few), philosophies(existentialism is big one- alien cultures are used to explore others, like epicureanism or stoicism), and ideas(like religion).
Basically, ST has more themes than SW. But! I will commend Star Wars for its exploration of one very deep thought- how easy it is to fall (go to the Dark Side), and the problem of fear in regards to that. This alone is probably why so many people can so easily identify with Star Wars, because it speaks to our awareness of human fraility and maybe explains why some people
can be so evil. It's all about choice.
Star Trek attempts to explore this, but not as well and succintly as Star Wars.
oh, and the technobabble thing. That serves to deter plenty of people XD
I think in a way, actually, it's not absolutely correct to compare the two - although both are film, one is exclusively movies, and the other is focused in episodes. They are in two different realms of storytelling -just like a novel is different from a comic book, even though they're both print.
They're just different, with different aspects, different accomplishments, different everything.
and there's my 2 cents =)
(edit: although, after seeing
btflash's avatar [kirk=lone ranger, spock= Tanto], I can see how ST also has its parallels to other stories.. but I still hold my position that ST's archetypes are less pronounced than SW.)