soft drug vs marihuana

soft drug and marihuana both are nouns.

Word	Noun	Adjective	Verb	Adverb
soft drug	Yes	No	No	No
marihuana	Yes	No	No	No

As nouns, marihuana is a hyponym of soft drug; that is, marihuana is a word with a more specific, narrower meaning than soft drug:

soft drug: a drug of abuse that is considered relatively mild and not likely to cause addiction
marihuana: the most commonly used illicit drug; considered a soft drug, it consists of the dried leaves of the hemp plant; smoked or chewed for euphoric effect

Other hyponyms of soft drug include bhang, cannabis, ganja, marijuana, haschisch, hash, hasheesh, hashish.

soft drug (noun)	marihuana (noun)
a drug of abuse that is considered relatively mild and not likely to cause addiction	the most commonly used illicit drug; considered a soft drug, it consists of the dried leaves of the hemp plant; smoked or chewed for euphoric effect
	a strong-smelling plant whose dried leaves can be smoked for a pleasant effect or pain reduction