Celosia argentea vs herb

Celosia argentea and herb both are nouns.

Word	Noun	Adjective	Verb	Adverb
Celosia argentea	Yes	No	No	No
herb	Yes	No	No	No

As nouns, herb is a hypernym of Celosia argentea; that is, herb is a word with a broader meaning than Celosia argentea:

Celosia argentea: weedy annual with spikes of silver-white flowers
herb: a plant lacking a permanent woody stem; many are flowering garden plants or potherbs; some having medicinal properties; some are pests

Other hypernyms of Celosia argentea include herbaceous plant.

Celosia argentea (noun)	herb (noun)
weedy annual with spikes of silver-white flowers	aromatic potherb used in cookery for its savory qualities
	a plant lacking a permanent woody stem; many are flowering garden plants or potherbs; some having medicinal properties; some are pests