cannabis vs marihuana

cannabis and marihuana both are nouns.

Word	Noun	Adjective	Verb	Adverb
cannabis	Yes	No	No	No
marihuana	Yes	No	No	No

As nouns, cannabis and marihuana are synonyms defined as:

cannabis and 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 synonyms of cannabis include ganja, marijuana.

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

cannabis: any plant of the genus Cannabis; a coarse bushy annual with palmate leaves and clusters of small green flowers; yields tough fibers and narcotic drugs
marihuana: a strong-smelling plant whose dried leaves can be smoked for a pleasant effect or pain reduction

Other hyponyms of cannabis include Cannabis sativa, ganja, marijuana, Cannabis indica, Indian hemp.

cannabis (noun)	marihuana (noun)
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	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
any plant of the genus Cannabis; a coarse bushy annual with palmate leaves and clusters of small green flowers; yields tough fibers and narcotic drugs	a strong-smelling plant whose dried leaves can be smoked for a pleasant effect or pain reduction