Difference between Rain and Rainwater

Rain

Part of speech: noun

Definition: Condensed water falling from a cloud. Any matter moving or falling, usually through air, and especially if liquid or otherwise figuratively identifiable with raindrops. An instance of particles or larger pieces of matter moving or falling through air.

Part of speech: verb

Definition: To have rain fall from the sky. To fall in large quantities. To issue (something) in large quantities.

Rainwater

Part of speech: noun

Definition: Rainfall.Water (for a house etc) sourced from rain which has not joined a spring, stream or river, pond, lake or sea.