fire iron vs coal tongs

fire iron and coal tongs both are nouns.

Word	Noun	Adjective	Verb	Adverb
fire iron	Yes	No	No	No
coal tongs	Yes	No	No	No

As nouns, coal tongs is a hyponym of fire iron; that is, coal tongs is a word with a more specific, narrower meaning than fire iron:

Other hyponyms of fire iron include fire tongs, fire hook, poker, salamander, stove poker, shovel.

fire iron (noun)	coal tongs (noun)
metal fireside implements	tongs for taking hold of burning coals