they have some similarites. Motorcycle helmets have some more vents, so air can be ventilated to the driver's head at speed. Racing helmets have less vents, as most of the cars have enclosed cockpits, and drivers often drive with the helmet visor cracked open, and have neck supports and a tube for a drink system. I do think F1 is one of the exceptions to this, as they are also open-cockpit and more motorcycle-like helmets