Topsoil and subsoil are distinct soil layers with different properties:
Topsoil: The uppermost layer, typically rich in organic matter, nutrients, and microorganisms. It's essential for plant growth and is often darker in color.
Subsoil: The layer beneath the topsoil, containing less organic matter and generally denser. It provides support for roots but is less fertile than topsoil.
During excavation, topsoil is often removed and preserved separately for later use in landscaping, while subsoil is typically used for backfilling or other less demanding applications.