old master vs Michelangelo Buonarroti

old master and Michelangelo Buonarroti both are nouns.

Word	Noun	Adjective	Verb	Adverb
old master	Yes	No	No	No
Michelangelo Buonarroti	Yes	No	No	No

old master (noun)	Michelangelo Buonarroti (noun)
a great European painter prior to 19th century	Florentine sculptor and painter and architect; one of the outstanding figures of the Renaissance (1475-1564)