In my little experience playing Forze ( mainly 5-6 hours clocked playing it at Best Buy) I always had the feeling that Forze was a little more arcade and GT more realist.
One example is the trajectory line you can display on the screen in Forza...

That trajectory line is just the best line around the track, a very useful training tool if you are a pro, it is a good reference point. Also, it makes for easier game play, especially if you are a noob to the genre.

one thing I like better in GT is the tracks. In forza, the track kinda feel like boring or uninspired... But Forza is a pretty decent game too. The crash are amazing and that a thing you dont find in GT... for now

OK, Fair enough. Atleast tell me this: have you been convinced?

I haven't seen anyone ask you this. Why  do you think Forza is better?

Funny, he never said Forza was better. He just said it was comparable to GT. But of course you can't see that because you are hell bent on convincing everybody that everything Xbox fails.