What is the difference between the bay and the sea?

Bays can form in any body of water: in lakes, oceans, seas and rivers, and seas always make up part of the oceans. Bays call that part of the water mass, which has a deepened shape, protruding into the land, and the seas can have only one common coast with the land, or can be surrounded on all sides by land and connect with the ocean only by a narrow strait. The main feature of the sea is a more elevated bottom compared to the oceanic one, special climatic conditions, etc. And the bays do not differ in their characteristics from the main pool.