A bus is any large vehicle that has many seats for passengers. A bus can mean a vehicle that is used within a city, has doors at the front and near the back for many passengers to get on and off frequently, and has seats that are as high as your upper back. Some people may call this a city bus. A coach usually means a bus that is used for long-distance transportation between cities, has one door at the front, has seats with backs high enough to support your head, and is more comfortable. The words bus and coach can be used a little differently in different parts of the English-speaking world. And the two words have additional meanings.

I really don't know! 😂 Here in Brazil "coach" is a kind of teacher!