Final answer:
The lithosphere is composed of the crust and the rigid upper mantle, while the asthenosphere is a partially molten material in the upper mantle that can flow plastically.
Step-by-step explanation:
The lithosphere and asthenosphere are divisions of Earth's upper mantle based on their mechanical properties. The lithosphere consists of the crust and the brittle, rigid portion of the upper mantle. It is about 100 kilometers thick and behaves as a solid. The asthenosphere, on the other hand, is partially molten material in the upper mantle that can flow plastically.