working man vs boxer

working man and boxer both are nouns.

Word	Noun	Adjective	Verb	Adverb
working man	Yes	No	No	No
boxer	Yes	No	No	No

As nouns, boxer is a hyponym of working man; that is, boxer is a word with a more specific, narrower meaning than working man:

working man (noun)	boxer (noun)
an employee who performs manual or industrial labor	a breed of stocky medium-sized short-haired dog with a brindled coat and square-jawed muzzle developed in Germany
	someone who fights with his fists for sport
	a workman employed to pack things into containers