achillea vs sneezewort

achillea and sneezewort both are nouns.

Word	Noun	Adjective	Verb	Adverb
achillea	Yes	No	No	No
sneezewort	Yes	No	No	No

As nouns, sneezewort is a hyponym of achillea; that is, sneezewort is a word with a more specific, narrower meaning than achillea:

achillea: any of several plants of the genus Achillea native to Europe and having small white flowers in flat-topped flower heads
sneezewort: Eurasian herb having loose heads of button-shaped white flowers and long grey-green leaves that cause sneezing when powdered

Other hyponyms of achillea include Achillea millefolium, milfoil, yarrow, Achillea ptarmica, sneezeweed yarrow.

achillea (noun)	sneezewort (noun)
any of several plants of the genus Achillea native to Europe and having small white flowers in flat-topped flower heads	Eurasian herb having loose heads of button-shaped white flowers and long grey-green leaves that cause sneezing when powdered