fetid horehound vs stinking horehound

fetid horehound and stinking horehound both are nouns.

Word	Noun	Adjective	Verb	Adverb
fetid horehound	Yes	No	No	No
stinking horehound	Yes	No	No	No

As nouns, fetid horehound and stinking horehound are synonyms defined as:

fetid horehound and stinking horehound: ill-smelling European herb with rugose leaves and whorls of dark purple flowers

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

fetid horehound (noun)	stinking 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