Hey!

A valley is an area which includes uphills or mountains with a river at the bottom. An elongated river is running below the mountains

An extensive area of land drained or irrigated by a river system.

Example : Indus valley, nile river, yellow river, etc.

Thank you.

A river valley refers to an elongated lowland between ranges of mountains, hills, or other uplands, often having a river or stream running along the bottom.

I hope this help