I think that the largest difference between it being pre-determined and being fake is that, while the match outcomes are planned ahead of time, many of the moves being done during a match actually hurt. Even take a simple body slam for example. The mat they're being slammed on isn't a glorified trampoline as I've heard some people say, but it's basically plywood with a thin layer of padding on top. Hitting that mat 30 times a night up to 200 times a year truly does take a toll on your body, even if you're performing as safely as possible. Then when you factor in guys flying out of the ring, getting hit with steel chairs, going through tables, etc., you begin to appreciate that they're putting their body on the line for entertainment- even if they know the final outcome well before the fans.
Then there's the whole other aspect which is the out of ring stuff. I've heard wrestling being compared to an action-packed soap opera, and I think that it's a good comparison. Just like other TV shows and movies, 99% of the time the people that are feuding with each other are at least acquaintances away from the ring, even if their characters would beat each other within an inch of their life. So yes, this part of wrestling is fake (including CM Punk's highly talked about promo last summer).
But one thing that many professional wrestlers don't care about is whether people call it fake or not (a few others might chew you out for saying it to their face, though). They get into the business knowing the stigma around the industry, and how it's viewed by the general public. Even the fans know that everything is pre-determined and pre-planned, but they watch because they appreciate the stories that the wrestlers are able to tell both in and outside the ring. That's why I think it's good that wrestling is aptly called "Sports Entertainment": it isn't 100% real, but they'll do everything they can to make sure the fans leave happy.
And if anyone has the time, you should check out a documentary called "Beyond the Mat." It was made in the late 90's, but it gives an in-depth look at the industry from the very top right down to the local companies, and it gives you a real appreciation of what these guys go through for the fans.