Ballota nigra vs black horehound

Ballota nigra and black horehound both are nouns.

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

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

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

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

Ballota nigra (noun)	black horehound (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