Layers of the soil are called horizons. Here are the horizons:
Humus
Topsoil
Subsoil
Fragmented rock
Bedrock
Once a soil has developed, it forms layers called horizons. Beneath a surface layer of a plant remains, the topsoil is rich in decomposed plants and animal matter. The subsoil is mainly mineral particles, with much less organic material. The fragmented rock/bedrock is primarily small stones, and beneath it lies all bedrock.
They are the same because they both are forced vibrations because both of them have a person or thing putting energy into the object. Also please clarify this question next time