pencil lead vs graphite

pencil lead and graphite both are nouns.

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

As nouns, graphite is a hypernym of pencil lead; that is, graphite is a word with a broader meaning than pencil lead:

pencil lead: mixture of graphite with clay in different degrees of hardness; the marking substance in a pencil
graphite: used as a lubricant and as a moderator in nuclear reactors

Other hypernyms of pencil lead include black lead, plumbago.

pencil lead (noun)	graphite (noun)
mixture of graphite with clay in different degrees of hardness; the marking substance in a pencil	used as a lubricant and as a moderator in nuclear reactors