Hi im gonna buy an electric guitar this summer and i was thinking of buying an SG special faded or a Les paul studio satin. th LP has a 50's rounded neck which is thick from what i've heard and the SG has a SG rounded neck. what are the differences between them? which is thicker...
They're all different. You can put 25 50's necks side by side and you won't find one that's the same as the next one. That's why its so important to try out as many Gibsons, even ones that are the exact same model, before you choose which one you actually like. Gibson are notorious for many things and inconsistency in neck size is definitely one of those.
Some are as big as tree trunks, some are less chunky. Play them and decide.
"Your sound is in your hands as much as anything. It's the way you pick, and the way you hold the guitar, more than it is the amp or the guitar you use." -- Stevie Ray Vaughan

"Anybody can play. The note is only 20 percent. The attitude of the motherfucker who plays it is 80 percent." -- Miles Davis

Guthrie on tone: https://www.youtube.com/watch?v=zmohdG9lLqY
The traditional 60s SG neck is fairly fat by modern standards. The 50s neck is significantly thicker, but still not a massive baseball bat style neck. And dazza027 is right; Gibson’s loose manufacturing tolerances do not produce consistent necks. So if you’re picky about necks you need to go to a store and pick the guitar you’ll buy.