Small Scooters are often termed boot scooters.  4mph top speed and usually with very basic specification.  Not necessarily the cheapest models in town, these are all designed and engineered to minimise size and weight so that, typically, they can be folded up or dismantled to lift in/out of a car boot.  Because they are designed for use on pavements and in shopping centres - comfort, carrying capacity, hill capability, ground clearance and range have all been compromised.

Usually 4mph but some capable of 6-8mph. Specification may be fairly basic but the faster ones will have 'road-legal' features.  This type of scooter often represents very good value for money, and they remain very popular for regular use for example on shorter distances around town.

Capable of up to 8mph and more often with a comprehensive level of sophistication, these are suitable for town and country use.
Most have a good range, and some deal with surprisingly rough and steep terrain, with ease.