What are the main differences between a lake and a sea in terms of their ecosystems 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 simpler ecosystems with less biodiversity, while seas have more complex ecosystems with a wider variety of species. Geographically, lakes are usually found inland and can be formed by glaciers or tectonic activity, while seas are typically found along Coastlines and are influenced by tides and currents.