graphite vs black lead

graphite and black lead both are nouns.

Word	Noun	Adjective	Verb	Adverb
graphite	Yes	No	No	No
black lead	Yes	No	No	No

As nouns, graphite and black lead are synonyms defined as:

graphite and black lead: used as a lubricant and as a moderator in nuclear reactors

Other synonyms of graphite include plumbago.

graphite (noun)	black lead (noun)
used as a lubricant and as a moderator in nuclear reactors	used as a lubricant and as a moderator in nuclear reactors