Downpour and Heavy rain

Downpour noun - A steady falling of water from the sky in significant quantity.

Heavy rain and downpour are semantically related in torrential rain topic. In some cases you can use "Heavy rain" instead a noun "Downpour", when it comes to topics like pouring rain.

Downpour and heavy rain are semantically related in torrential rain topic. You can use "Downpour" instead a noun phrase "Heavy rain", if it concerns topics such as pouring rain.