Terminal literally means ending or final stop. A terminal is a big train station that is usually the final stop on a main line. You find these in big cities like London and Paris. Trains enter one side of the station and then they go back out the same way. There is no thru line. A basic train station is found along a main line. The train stops and then continues going in the same direction to the next station. It is not the final stop on the line. For airplane travel, all "stations" are called terminals, even if you are just connecting to another flight. It may not be the end of the line, but it's still "final" because passengers get off the plane.

Terminal is much less specific. A Terminal is an end point or a stopping point on any type of route. There are train terminals, airplane terminals, and bus terminals.