purslane speedwell vs veronica

purslane speedwell and veronica both are nouns.

Word	Noun	Adjective	Verb	Adverb
purslane speedwell	Yes	No	No	No
veronica	Yes	No	No	No

As nouns, veronica is a hypernym of purslane speedwell; that is, veronica is a word with a broader meaning than purslane speedwell:

purslane speedwell: North American annual with small white flowers widely naturalized as a weed in South America and Europe
veronica: any plant of the genus Veronica

Other hypernyms of purslane speedwell include speedwell.

purslane speedwell (noun)	veronica (noun)
North American annual with small white flowers widely naturalized as a weed in South America and Europe	any plant of the genus Veronica