Stream is the word used for a channel of flowing water. A river is a large stream.
Streams originate in high ground, though the slope is not always noticeable with the naked eye. They can be fed by a number of sources. Rain and melting snow and glaciers can feed streams.
Some streams run out of lakes. Streams can also he formed by shifting earth releasing underground water.
When the ground becomes saturated (cannot hold any more water), the water gathers on the surface and the force of gravity channels it through the terrain in a stream. Depending on the hardness and density of the land, the stream develops quickly or slowly.
Rivers are fed by smaller streams. They barrel through the terrain, ultimately carrying water and sediment to the ocean.
Inevitably, however, the eroding, or wearing away, force of running water cuts through the earth. Because gravity forces everything down to the lowest point, rivers continue until they reach the ocean, the lowest level of land—sea level.
From high ground to low, rivers erode and change the landscape. Stages 1,2, and 3 represent youth, adulthood, and old age in a river, as well as its progress to the sea.