hard hat vs tin hat

hard hat and tin hat both are nouns.

Word	Noun	Adjective	Verb	Adverb
hard hat	Yes	No	No	No
tin hat	Yes	No	No	No

As nouns, hard hat and tin hat are synonyms defined as:

hard hat and tin hat: a lightweight protective helmet (plastic or metal) worn by construction workers

Other synonyms of hard hat include safety hat.

hard hat (noun)	tin hat (noun)
a lightweight protective helmet (plastic or metal) worn by construction workers	a lightweight protective helmet (plastic or metal) worn by construction workers
a worker skilled in building offices or dwellings etc.