Hmm... to better compare NFS and GT,

NFS - better for car tuning addicts... ung palitan ung sasakyan nito, niyan, at kada palit sa mas maganda/mas mahal e siguradong may tataas sayo na stats.

GT- better for those really into simulations kasi most of the cars run the way they "should" be in the real world. And, modifying your car's aesthetics won't do you good in races, only performance upgrades will.

I play both... and can't still figure out to why I drive so good in GT (without bumping to walls, other cars, etc) and drive lousily in NFS (really bumping to almost everything, except for NFS 3 that is). One reason I know is because may series ng NFS (Hot Pursuit at Most Wanted) na habulan ng pulis (may chopper pa nga na naglalaglag ng explosives), pero besides that, hindi ko na alam kung bakit.