Lithosphere
The Lithosphere is the solid shell of planet Earth. That means the crust and part of the upper mantle that behaves elastically on time scales of thousands of years or greater. The lithosphere is broken into tectonics plates.
Asthenosphere
The Asthenosphere is the highly cruel mechanically weak strongly-deforming region of the upper mantle of the Earth, it lies under the Lithosphere at depths between 100 and 200 km below the surface, but perhaps extending as deep as 700 km and it's part of the upper mantle.