fireweed vs weed

fireweed and weed both are nouns.

Word	Noun	Adjective	Verb	Adverb
fireweed	Yes	No	No	No
weed	Yes	No	Yes	No

As nouns, weed is a hypernym of fireweed; that is, weed is a word with a broader meaning than fireweed:

fireweed (noun)	weed (noun)
tall North American perennial with creeping rootstocks and narrow leaves and spikes of pinkish-purple flowers occurring in great abundance in burned-over areas or recent clearings; an important honey plant	street names for marijuana
an American weedy plant with small white or greenish flowers	a black band worn by a man (on the arm or hat) as a sign of mourning
	any plant that crowds out cultivated plants

fireweed (verb)	weed (verb)
	clear of weeds