Types of street motorcycles

Choppers: Off-road motorcycle based on a cruiser-style frame with long rake (longer front forks). They are also usually bare of various accessories and other non-essential parts. Many are created more for show than rideability.
 
Harley-Davidson Softail Heritage Classic. A typical "cruiser" design
An Italian 125 cc Cagiva Planet.

A "standard" or "naked" motorbikeCruisers: A range of small to large motorcycles designed for comfort and looks with a relaxed upright or reclined seating position. They often use lots of chrome and may be highly customised.
Electric motorcycles: Nearly silent, zero-emission electric motor-driven vehicles. Operating range and top speed suffer because of limitations of battery technology. Fuel cells and petroleum-electric hybrids are also under development to extend the range and improve performance of the electric motors CUB Motorcycle

Mini bikes: Very small bikes designed to be simple run-around fun for both children and adults. Generally they have no hand-operated clutch or gearbox to simplify operation. Also known as Mini Motos. Not street-legal in most countries and jurisdictions. May be used for racing by all age levels.
Mopeds: Small, light, inexpensive, efficient rides for getting around town. Usually started by pedalling (motorcycle pedals = moped). Mopeds typically have an engine mounted to the frame with a chain supplying the drive force to the wheel.

Naked bikes/Standard/Street bikes: Naked bikes have a riding position midway between the forward position of a sports bike and the reclined position of a cruiser. Unlike touring bikes, naked bikes often have little or no fairing (hence the title). Luggage capabilities are often an optional extra. Naked bikes are popular for commuting and other city riding because the upright riding position gives greater visibility in heavy traffic (both for the rider and to other road users) and are more comfortable than the hunched over sport bikes. Naked bike and standard are not fully interchangeable terms. Naked refers to the lack of bodywork, and standard refers to the upright riding position. http://www.yingangmotorcycle.com

Scooters: Motorbikes with a step-through frame, generally smaller wheels than those of a traditional motorcycle and an engine mounted near the rear wheel on the swingarm. Can be ridden without straddling any part of the bike and usually features a floorboard. Available in sport, commuter, and touring models and wide Bearings variety of engine sizes from the standard 50 cc to 850 cc. auto bearings