You're absolutely right! The asthenosphere and lithosphere are both parts of Earth's mantle.

Here's a breakdown:

* Lithosphere: This is the rigid, outermost layer of Earth, including the crust and the uppermost part of the mantle. Think of it as a strong, brittle shell. It's broken into tectonic plates that move and interact, causing earthquakes, volcanoes, and mountain ranges.

* Asthenosphere: This layer lies beneath the lithosphere. It's a semi-solid, partially molten layer of the upper mantle. It's hot and behaves like a very viscous fluid, allowing the tectonic plates to move on top of it.

So, in summary:

* Earth's structure: Crust -> Lithosphere -> Asthenosphere -> Lower Mantle -> Outer Core -> Inner Core