rock group vs rock band

rock group and rock band both are nouns.

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

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

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

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