brain truster vs consultant

brain truster and consultant both are nouns.

Word	Noun	Adjective	Verb	Adverb
brain truster	Yes	No	No	No
consultant	Yes	No	No	No

As nouns, consultant is a hypernym of brain truster; that is, consultant is a word with a broader meaning than brain truster:

brain truster: an expert adviser involved in making important decisions but usually lacking official status
consultant: an expert who gives advice

Other hypernyms of brain truster include adviser, advisor.

brain truster (noun)	consultant (noun)
an expert adviser involved in making important decisions but usually lacking official status	an expert who gives advice