Answer and Explanation:
A river is a reservoir of fresh water and is a natural watercourse. It normally flows into an ocean or sea. Sometimes it joins a lake or other river. Rivers constitute complex fluvial ecosystems that can host several thousand species of living beings and that is, therefore, the support of a complex network of ecological relationships. A stream on the other hand is a small river, it has a low flow, which may even disappear in the dry season, summer or winter, depending on the rainy season for its existence. A stream can also be a narrow channel between islands. Generally a river is bigger and deeper compared to a stream. However it should not be considered as a general rule. Flexibility is vital because some streams are larger than some rivers.