knotty pine vs pine

knotty pine and pine both are nouns.

Word	Noun	Adjective	Verb	Adverb
knotty pine	Yes	No	No	No
pine	Yes	No	Yes	No

As nouns, pine is a hypernym of knotty pine; that is, pine is a word with a broader meaning than knotty pine:

knotty pine: pine lumber with many knots; used especially for paneling and furniture
pine: straight-grained durable and often resinous white to yellowish timber of any of numerous trees of the genus Pinus

knotty pine (noun)	pine (noun)
pine lumber with many knots; used especially for paneling and furniture	a coniferous tree
	straight-grained durable and often resinous white to yellowish timber of any of numerous trees of the genus Pinus

knotty pine (verb)	pine (verb)
	have a desire for something or someone who is not present