A tractor is a big vehicle usually driven by farmers. Tractors are used to pull ploughs and harvesters, and for pulling wagons full of hay or other loads. Tractors can be used for pulling other vehicles out of mud if they get stuck.
Tractors are designed to run on mud and dirt not smooth roads, which is why their back wheels are so big and have tyres with such deep tread.
A train is a rail vehicle. It is usually made up of a large number of carriages that carry either people or goods, and one or more engines that pull it along the rails.
A tram, or streetcar is a kind of small train that also runs on railway tracks. Trams are typically seen in suburban streets instead of trains or buses.
