The short answer to the first question; none. The long answer is different, but in the terms of the law, a scooter is a motorcycle, just the same way a cruiser is a motorcycle, a sports bike is a motorcycle, etc.
Both are known as Powered Two Wheelers (PTW), in other words, two wheels and an engine. There are some differences though;
- Most scooters are automatic: Scooters are automatic, there is no gearbox. But then, there are some motorcycles nowadays that have no gearbox either.
- Scooters normally have no foot brake: Since there is no gearbox, the left handle is the rear brake.
- Scooters have a step-through frame: the gas tank is under the rider and the rider’s feet don’t need to go over the bike when getting on, much like a female bicycle.
- Scooters often have a cargo platform: the space between the rider and the handlebars is open and can be used to store stuff, like shopping bags. Often there is even a hook to secure the bag in-between the legs of the rider.
- Scooters often have smaller wheels: Wheels are usually smaller because speeds are lower, and need to maneuver in the city, the “normal” habitat where you will find scooters.
- Scooters often have small displacement engines: traditionally scooters have smaller engines, typically 125 to 200 cc, but nowadays you’ll find then with even 650 cc.
For the rest, they are like any normal motorcycle, they behave the same way, use counter steering, and usually have a place for a pillion.
So in essence, there is no real difference between both types; they are motorcycles in all terms of the word. In most states, you need the same license to ride one, and the same protection.
So why the bad blood. You will often hear motorcycle riders say that scooters are not like normal motorcycles, that the riders are less, etc. Scooters are looked down on.
Personally, I think it’s because of old movies, particularly British ones that highlighted the Mods against the Rockers; scooter riders against motorcycle riders. That set the tone, and has carried on ever since. In riding skills, you can ride either vehicle without any adaptation, you face the same dangers and you get the same emotional feeling when riding either. Both are fun and dangerous.
Some motorcycles are far faster than scooters – particularly sports bikes, but most normal motorcycles are as fast as their equivalent scooter.
Do you wave at scooters when you ride a motorcycle, and vice versa? I do.