Okay, here we go. All of these have two wheels. If I've missed anything, or you'd like my opinion on a specific two wheeled vehicle classification, let me know.
Motorcycle
- More than 15HP
- 16" or larger wheels
- Manual transmission or DCT automatic (not a variator with a belt)
Moped
- "Functional" pedals; not practical, just functional
- Under 80cc
- 16" or larger wheels
- Variator/belt transmission
- Few or no plastics
- These came up in the late 1970s to comply with various "motor-driven cycle" legal allowances
- You rest your feet on the pedals
- Can be "throw your leg over" or step through
- Generally have a max speed of 30MPH stock
Scooter
- Any engine size (I believe the Suzuki Burgmann 650 is the largest, could be wrong)
- Step through, you sit on it like a toilet
- Flat floor pan for your feet, or flat foot "floorboards" to the sides of a low center hump
- Lots of plastics
- Variator/belt transmission
- Most of these have 14" maximum wheel size and comparatively fat tires
Noped
- Basically a moped without the pedals
- Foot pegs
- These came in the early to mid 1980s
- Can have smaller wheels, but the tires are not fat like scooter tires
Scooter cycle
- Looks lilke a small motorcycle; clearly intends for you to think it is
- Variator/belt transmission
Motorized bicycle (MB)
- Began its life as a regular pedal bicycle without power assist
- Has an added internal combustion engine for power assist
- ICE engine can drive the rear wheel with a second chain and sprocket, or the front or rear wheel with a pinch roller, very rarely with a pusher trailer; kits also exist to replace the bottom bracket with a freewheel sprocket that the engine drives, with power going to the wheel via the pedal chain
- In rare cases, these were manufactured this way, generally very old ones
E-Bike
- Pedal bicycle with electric power assist
- Many of these are factory made now
- These can also be made the same way MBs are, by adding an electric motor: -- Pinch roller drive -- Hub motor drive -- Bottom bracket drive
Minibike
- Similar to a noped, but extremely small
- Small wheels and fat little tires
- May not have brakes at all, if it does, they're really bad
- Pull start
Dirtbike
- A small motorcycle designed for offroad use
- May not be street legal
- Small ones for kids may be variator driven