Ping-Pong vs ping pong

Ping-Pong and ping pong both are nouns.

Word	Noun	Adjective	Verb	Adverb
Ping-Pong	Yes	No	No	No
ping pong	Yes	No	No	No

As nouns, Ping-Pong and ping pong are synonyms defined as:

Ping-Pong and ping pong: a game (trademark Ping-Pong) resembling tennis but played on a table with paddles and a light hollow ball

Other synonyms of Ping-Pong include table tennis.

Ping-Pong (noun)	ping pong (noun)
a game (trademark Ping-Pong) resembling tennis but played on a table with paddles and a light hollow ball	a game (trademark Ping-Pong) resembling tennis but played on a table with paddles and a light hollow ball