what you hear on a pro record is a reflection of the art of studio work.
First off, there are multiple guitar tracks. There might be just say, two guitars-rhythm and lead-but the rhythm track is most likely multiple tracks in layers to beef up the sound.
for ex-the rhythm track you hear might be a low-endy guitar tone mixed with a mid-y guitar tone and a more highs based guitar tone. Apart they are thin, but mixed carefully, they sound fat and crushing.
Or it simply might be the track tripled.
Also, Compression and other recording effects are present. There are all sorts of special EQs, etc to give tracks certin sounds, and you have to know how to use them..it's a art form.
Also, are you using studio moniters? They have a flat EQ curve-all other types of speakers "color" the sound, so what you are hearing will sound good on your system, but on anyone else's, it sounds like crap.
I suggest you get a few book on recording and read up. Luckily these days, recording stuff is going down in cost, and those books can show you tricks to do it as cheaply as possible while getting good sound.