Full Face Bike Helmets

I want to buy a helmet to ride a bike, and someone sell me a dirt bike helmet ... Is also suitable for riding bike? Helmet face are different? (As may be lighter or wider range of vision ...)

Yes. You'll be relatively safe using the headset on your motocross bike, but the motocross helmets are heavy and not very well ventilated. Sell Motocross and use the money to get a cover made for bikes.