Known to: when we want to talk about some fact that people have learned.

• Lions have been known to occasionally kill large beasts like elephants, giraffes, and rhinos.
• Elephants are known to communicate with seismics, vibrations produced by impacts on the earth's surface or acoustical waves that travel through it.

Known as: when we want to talk about the name of somebody or something or its definition.

• Some male Asian elephants are tuskless and are known as Muknas
• Lions are big cats known as the "King of the Jungle".