R.V. vs camping bus

R.V. and camping bus both are nouns.

Word	Noun	Adjective	Verb	Adverb
R.V.	Yes	No	No	No
camping bus	Yes	No	No	No

As nouns, camping bus is a hyponym of R.V.; that is, camping bus is a word with a more specific, narrower meaning than R.V.:

R.V.: a motorized wheeled vehicle used for camping or other recreational activities
camping bus: a recreational vehicle equipped for camping out while traveling

Other hyponyms of R.V. include camper, motor home, beach buggy, dune buggy.

R.V. (noun)	camping bus (noun)
a motorized wheeled vehicle used for camping or other recreational activities	a recreational vehicle equipped for camping out while traveling