endothelium vs. epithelium

endothelium vs. epithelium: What's the difference?

Endothelium is a type of epithelium. Epithelium is animal tissue, such as skin, that covers a surface or lines a cavity and performs secretory, transporting, or regulatory functions. Endothelium is composed of a single layer of smooth, thin cells that lines the heart, blood vessels, lymphatics, and serous cavities.