First, the motorcycle is an umbrella term, a two-wheeled or sometimes three-wheeled motor vehicle designed for various purposes such as commuting, traveling, and sports. All scooters, mopeds, and underbones are called motorcycles, but not all motorcycles are scooters, mopeds, and underbones, such as dirt bikes, and vintage motorcycles.

Mopeds and scooters are distinct in their own ways and are typically categorized separately from other motorcycles. However, these terms are often used interchangeably, which can be confusing for those who are not familiar with the specific differences.

A moped is a small low-powered motorcycle with an engine capacity no greater than 50cc. In some countries, a moped can be any motorcycle with an engine capacity below 100 cc. Historically, the term ‘moped’ is a combination of ‘motor’ and ‘pedal.’ The earliest mopeds were motorbikes with bicycle pedals, typically used in emergencies.

• Design: Mopeds usually have a small engine (under 50cc) and some can be pedaled like a bicycle.
• Usage: Suitable for short-distance commuting and typically have lower speeds.
• Engine Size: Generally less than 50cc
• Legal Classification: In some regions, mopeds may not require a motorcycle license but do require registration and insurance.

A scooter, also known as a motor scooter, is a type of motorcycle with a step-through frame, a seat, and a transmission that shifts without the operator having to use a clutch lever and a platform for the rider’s feet. This means that you can step into them rather than having to climb aboard and swing a leg over.

• Design: Scooters typically have a step-through frame and a platform for the rider’s feet. They usually come with an automatic transmission and smaller wheels (10-16 inches).
• Usage: Ideal for short commutes and city riding due to their ease of parking and maneuverability.
• Engine Size: Generally ranges from 50cc to 250cc.

A moped is a scooter with an engine capacity of 50ccs or less, while a scooter with a higher engine capacity is not classified as a moped. You may see some scooters with engine capacities of 300cc, 500cc, 900cc, etc, but if it has a platform for your feet, it is still technically a scooter.

An underbone is a type of motorcycle that features a unique step-over frame design where the engine is positioned beneath the rider, between their feet, but without a platform for the rider’s feet.

• Design: Underbones have an open frame structure with the engine mounted below the main frame. They often have a manual transmission.
• Usage: Commonly used in Southeast Asia and South Asia for daily commuting and long-distance travel.
• Engine Size: Usually ranges from 100cc to 150cc.

Both underbones and scooters have frames. But Underbones feature step-over frames with the engine positioned between the rider’s feet. Unlike conventional motorcycles, underbones lack a backbone frame, which is typically where the fuel tank is located. 

Scooters generally feature step-through frames with their engines usually positioned beneath the seat near the rear wheel.

Mopeds, scooters, and underbones are easy to handle, with low maintenance, and affordable prices, they are loved by people for commuting, delivering express, grocery shopping, and short trips.

Motorcycles are popular worldwide due to their efficiency, speed, and relatively low cost, making them a preferred mode of transportation in both urban and rural areas.