A tributary and a distributary are both bodies of freshwater that eventually meet with or diverge from rivers, but they differ in the direction that they flow. A tributary is a stream that flows into a larger river. A distributary is a stream or small river that splits off from a larger river and flows in a different direction.
The process in which a distributary branches off from a river is called bifurcation.
Tributaries also have a variety of special terms attached to them. The river that tributaries flow into is called a mainstream. A tributary is also known as an affluent, and the point where the tributary meets with the mainstream is called the confluence. In addition, tributaries can be called "left-bank tributaries" or "right bank-tributaries" based on the side of the river on which they're located.
The Balikh is one example of a stream that originates in the mountains and eventually combines with the Euphrates River and becomes a left-bank tributary. In Wyoming, there's a small creek called the North Two Ocean Creek. This creek has a distributary that splits into two streams: one that flows to the Atlantic Ocean and one that flows to the Pacific Ocean.