old hand vs warhorse

old hand and warhorse both are nouns.

Word	Noun	Adjective	Verb	Adverb
old hand	Yes	No	No	No
warhorse	Yes	No	No	No

As nouns, old hand and warhorse are synonyms defined as:

old hand and warhorse: an experienced person who has been through many battles; someone who has given long service

Other synonyms of old hand include old-timer, old stager, oldtimer, stager, veteran.

old hand (noun)	warhorse (noun)
an experienced person who has been through many battles; someone who has given long service	horse used in war
	a work of art (composition or drama) that is part of the standard repertory but has become hackneyed from much repetition
	an experienced person who has been through many battles; someone who has given long service