Summary: 1.A river basin is a body of land where water from different sources converge while a watershed may also mean the same as a water basin, but it also refers to the drainage divide or land form that divides river systems.atersheds are considered part of a water basin. In other regions of the world, watersheds are the drainage divides that cut through a river system. While both a river basin and a watershed are land forms, they have different functions in our ecology.