Motorcycles vary more widely in their CCs which is also called engine displacement. (“cc” stands for “cubic centimeters”).
The larger the volume of the cylinders (or the higher the CC), the more air and fuel the engine is able to suck in at once, and the more power the engine will be able to generate. Higher CC, faster bike!
However, a motorcycle tends to sacrifice fuel efficiency for higher CCs, as larger cylinders will deplete the amount of gas in the bike faster.
Conversely, a smaller CC number may generate less power, but likely increase the motorcycle’s miles per gallon. (This is also true if you opt for a scooter)