backroom boy vs adviser

backroom boy and adviser both are nouns.

Word	Noun	Adjective	Verb	Adverb
backroom boy	Yes	No	No	No
adviser	Yes	No	No	No

As nouns, adviser is a hypernym of backroom boy; that is, adviser is a word with a broader meaning than backroom boy:

backroom boy: an expert adviser involved in making important decisions but usually lacking official status
adviser: an expert who gives advice

Other hypernyms of backroom boy include advisor, consultant.

backroom boy (noun)	adviser (noun)
an expert adviser involved in making important decisions but usually lacking official status	an expert who gives advice