risk vs gamble

risk and gamble both are nouns.

Word	Noun	Adjective	Verb	Adverb
risk	Yes	No	Yes	No
gamble	Yes	No	Yes	No

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

Other hyponyms of risk include chance, crapshoot.

As verbs, risk and gamble are synonyms defined as:

Other synonyms of risk include adventure, chance, hazard, run a risk, take a chance, take chances.

risk (noun)	gamble (noun)
a venture undertaken without regard to possible loss or injury	a risky act or venture
the probability of being exposed to an infectious agent	money that is risked for possible monetary gain
the probability of becoming infected given that exposure to an infectious agent has occurred
a source of danger; a possibility of incurring loss or misfortune

risk (verb)	gamble (verb)
expose to a chance of loss or damage	play games for money
take a risk in the hope of a favorable outcome	take a risk in the hope of a favorable outcome