The lithosphere and asthenosphere are names of layers in the earth and are defined by the physical properties of each layer. The lithosphere is defined as the outer layer of planet Earth which is brittle. Brittle objects will break in pieces if you hit them with enough force; they do not bend or deform like playdoh. The asthenosphere is ductile, which means it will bend or deform like playdoh if you apply enough force to it.

The lithosphere is the outermost rock layer in Earth, and the asthenosphere is the layer right below the lithosphere. Both are made of similar chemicals (for example: oxygen, silicon, aluminum, magnesium, iron). At the boundary where the lithosphere touches the asthenosphere, both layers have the exact same chemistry (we call this the same composition). The only difference is that the asthenosphere is not as brittle (not as solid) as the lithosphere, mostly because the asthenosphere is hotter. (It is hotter because it is deeper in the earth.)

The lithosphere and the asthenosphere are both part of the earth's mantle. They are both molten rock and very hot (they both like when lava comes out the top of a volcano)

They're both solid rock, but the asthenosphere is more plastic, allowing the rock in the asthenosphere to flow over long periods of time.