hard coal vs anthracite

hard coal and anthracite both are nouns.

Word	Noun	Adjective	Verb	Adverb
hard coal	Yes	No	No	No
anthracite	Yes	No	No	No

As nouns, hard coal and anthracite are synonyms defined as:

hard coal and anthracite: a hard natural coal that burns slowly and gives intense heat

Other synonyms of hard coal include anthracite coal.

hard coal (noun)	anthracite (noun)
a hard natural coal that burns slowly and gives intense heat	a hard natural coal that burns slowly and gives intense heat