I need help choosing a dirt bike?

[a l l e n]

Okay so I am about 148lbs, im 6' 2" and I am 17. What would be a bike size and brand that suits me. Also what is the difference between Supercross and Motorcross?
Ive gotten great feedback but i figured i would add more info. I have only experience on four wheeler and i have ridden a smaller bike. I wanna start motorcross then move on up.....so theres no point of buying a begining bike if im going to do motorcross...

 

[auburn]

The first answerer has given you good advice and great suggestions as to what bikes would be good for you. I can only agree that if riding trails the crf250x or ttr250 would be great or if racing the crf250r, kx250f or any of the other known brand 250f's.

If you are considering taking up mx racing the 4 strokes are the way to go and you would not do supercross until you had the sufficient skill levels to do so. Supercross is usually done on a tighter track with higher difficulty of jumps. Motocross is on a more open track with straights and while still having jumps they are not usually as difficult or close together. Both take skill but each skill is different. Bike set up is a lot different for each discipline as well.