Hub motors, also known as
in-wheel motors, require electric power to run (which is provided by the
batteries) These motors are typically attached to the wheel. You’ll find that
single motor hubs have a normal power wattage of 350W, 500W or 750W.
On the other hand, belt driven
motors, or simply belt motors, are placed under the deck. These motors connect
to the wheels via gears and clutches. Belt motor systems were used mainly until
2015. After that, hub motor systems gained popularity.
To answer the second question, hub motors are much more efficient. They are easily upgradable, the brakes have a stronger and quicker response time, and they have fewer moving parts (which means that there are fewer chances of a breakdown).