black horehound vs Ballota nigra

black horehound and Ballota nigra both are nouns.

Word	Noun	Adjective	Verb	Adverb
black horehound	Yes	No	No	No
Ballota nigra	Yes	No	No	No

As nouns, black horehound and Ballota nigra are synonyms defined as:

black horehound and Ballota nigra: ill-smelling European herb with rugose leaves and whorls of dark purple flowers

Other synonyms of black horehound include black archangel, fetid horehound, stinking horehound.

black horehound (noun)	Ballota nigra (noun)
ill-smelling European herb with rugose leaves and whorls of dark purple flowers	ill-smelling European herb with rugose leaves and whorls of dark purple flowers