rock band vs rock group

rock band and rock group both are nouns.

Word	Noun	Adjective	Verb	Adverb
rock band	Yes	No	No	No
rock group	Yes	No	No	No

As nouns, rock band and rock group are synonyms defined as:

rock band and rock group: a band of musicians who play rock'n'roll music

rock band (noun)	rock group (noun)
a band of musicians who play rock'n'roll music	a band of musicians who play rock'n'roll music