Yeah, the posts that have been made thus far pretty much explain the differences.
The primary differences between a Studio and a Standard are basically the binding, plain (non-flame) maple caps. For a while they both came with the same pick-ups (
the 490R/489T combination), but the newer Standards do come with the Burstbuckers. The newer Studios also, I believe, have dot inlays whereas the older ones had the trapezoid inlays. Also, on the older Studios, most of the fretboards were Ebony. Now, I think only the alpine white Studios get the Ebony fretboard and the rest get Rosewood.
I'm not sure about the Studios having 2-piece bodies. As far as I know, they have 1-piece Mahogany bodies, although the Norlin-year Les Pauls had the 2-piece "pancake" bodies.
I have 2 Les Paul Studios, a 1990 and a 1994, and I love 'em. You'd be hard pressed to tell the difference tone-wise between them and a Standard of that era.
The double-cutaways, if I remember correctly, have a wrap-around tailpiece. I'm sure that makes some tonal difference of sorts, but I've never A/B-ed a double-cutaway versus a regular Les Paul.
As someone mentioned earlier, the Studio's are a great bang for the buck, and they are most certainly a "real" guitar. You can find used ones on the cheap pretty regularly. I'm actually trying to sell one of mine (for $600.00 US) to get a white Studio that a guy I know is selling. But on average they go for between $600.00 - $750.00 US from what I've seen of late.
But also as someone else mentioned...go play some. You'll know which one is right for you.