What is the difference between express, mail and superfast trains?

The speed of express trains is more than 55 kilometres per hour. These are counted among semi-priority trains. The name of express trains starts with the name of a person, city or place. In comparison to express and superfast trains, the speed of mail trains is less. These trains run at a speed of about 50 kilometres per hour. 
These trains connect cities as well as long-distance stations. These trains stop at halts many times. Superfast trains run at very high speeds. Their speed is about 110 kilometres per hour. Their stoppage is also less.