Electric Motorcycles & Electric Bicycles

This is a good article on the types of electric bicycle motors comparing front hub-types, gear-type, rear hub-type and mid-mounted types :

https://www.bikeradar.com/advice/buyers-guides/electric-bike-motors/

It also goes on the explain the electric bicycle power and torque as used in various assistance (usage) levels.

However, without explicitly saying so, the key to assistance is the usage level for the specific duration and distance requirements as well as the grades of terrain and the friction (rocks, mud, gravel, ... etc) that the user will experience.

All of these factors can and will drain the rider of energy as much as the battery pack. So specific rider usage models may also require specific battery pack options as well to plan for specific outing trips.