+1 for what Nismo put up there.
The only real difference is performance of the computer. This may be what your friend was referring to in 'lower quality spec' and it is pretty much true.
This only really holds true at the very high end of things, essentially only for high end brand new games with all the pretty things turned on. Your top of the line PC will always beat the top of the line Laptop, due to .. well, size, heat, etc. The actual laptop case is rather limiting.
HOWEVER, if you aren't using your PC/laptop for hardcore gaming, you won't notice any difference between the two. It's like a car that is stupidly quick from 100-200kmh, but the same 0-100.. when you only drive at legal speeds.