What are the key differences between a lake and a sea in terms of their ecological characteristics and geographical features?

Lakes are smaller bodies of freshwater surrounded by land, while seas are large bodies of saltwater connected to the ocean. Lakes have limited biodiversity and are more vulnerable to pollution, while seas have higher biodiversity and are influenced by tides and currents. Geographically, lakes are inland and can be formed by glaciers or tectonic activity, while seas are coastal and influenced by the ocean.