fire tongs vs pair of tongs

fire tongs and pair of tongs both are nouns.

Word	Noun	Adjective	Verb	Adverb
fire tongs	Yes	No	No	No
pair of tongs	Yes	No	No	No

As nouns, pair of tongs is a hypernym of fire tongs; that is, pair of tongs is a word with a broader meaning than fire tongs:

fire tongs: tongs for taking hold of burning coals
pair of tongs: any of various devices for taking hold of objects; usually have two hinged legs with handles above and pointed hooks below

Other hypernyms of fire tongs include fire iron, tongs.

fire tongs (noun)	pair of tongs (noun)
tongs for taking hold of burning coals	any of various devices for taking hold of objects; usually have two hinged legs with handles above and pointed hooks below