A synchronous polar orbit satallite crosses the equator at the same time each day while the sun synchronous polar satellite appears in the sky at the same time every few days. the sun synchronous allow for greater temporal and spatial monitoring under same conditions and also have finer resolution as the polar synchronous imagery is at the continental scale.

The Earth orbit in which satellites appear to be stationary is called the, "Geostationary Orbit". Some call it a synchronous orbit.

Once, it is in a synchronous orbit with Earth

Synchronous rotation is when the time of rotation equals the time of the orbit, resulting in a situation where the same side of a body is pointing inward like in the moon.

In simple terms, any body in space (e.g. an asteroid or satellite) is said to be synchronous when its own movement (i.e. orbit) corresponds to that of another. In other words, a "geo"synchronous satellite would be in orbit around earth, while Jupiter (and the other 7/8 planets) are heliosynchronous (orbiting the sun).