A bus has rubber tires and drives on a road. A bus is normally diesel powered although in places like Seattle may also be powered by electricity from overhead wires (catenary)

A Tram has train wheels, rolls on tracks-sometimes placed in a road, sometimes not. It typically is powered by Electricity from overhead wires. It may have one or two cars and resembles a trolley car. Trams are all over Europe and are normally used for commuting. Some tram lines are quite long and replace or supplement real railroad passenger trains.

Is this a sufficient explanation?