Yeah, the big difference is the OS, with the Pro 2 being able to run pretty much any program you install on it. It's convenient, but you'll find that without a discrete GPU, even the power of a Core i5 won't make this your primary gaming machine. It's good for low requirements games, or just playing so more intensive games on lowered settings.
That being said, the digitizer screen is where the huge gap in pricing comes from. That's the thing that allows you to write on the screen with a stylus without making it feel like you're trying to write on plastic using a sausage (read:using a stylus with an Ipad). It's a WONDERFUL tool for students and some professionals... and utterly useless for anyone else. Personally I'm a huge fan of it and wouldn't be able to go through class and note taking without a stylus anymore, but it is way too expensive if you don't plan to use it at all.
Also keep in mind that Windows RT, which is used with the regular Surface 2, has been failing to garner any kind of relevant support from app developers for two years now, meaning that the app ecosystem is extremely poor when compared to what you will see on ipads and even android devices. As g-unit already mentioned, you won't be able to install any kind of windows programs on the RT, you'll need an app. I advise doing some research to make sure that the apps you need for your tablet are available on RT before you make a move and buy a Surface 2. And if money isn't a concern... definitely go all the way with the Surface Pro 2. I wouldn't name it the best tablet for the money by a LONG shot, but it's still one of my favorite tablets on the market right now.