In general, horses under 147cm are categorised into pony - the term pony doesn't refer to a specific breed.
Ponies are generally considered friendly and have excellent durability. It is often used for children who are learning to ride and also can be treated as a mascot character.
Ponies are small but they are amazingly athletic and can run about 40km per hour.
Japanese native pony which were mentioned previously are also categorized as ponies.
Here are some examples of ponies, excluding Japanese native pony.