chance event vs lottery

chance event and lottery both are nouns.

Word	Noun	Adjective	Verb	Adverb
chance event	Yes	No	No	No
lottery	Yes	No	No	No

As nouns, lottery is a hyponym of chance event; that is, lottery is a word with a more specific, narrower meaning than chance event:

chance event: anything that happens suddenly or by chance without an apparent cause
lottery: something that is regarded as a chance event

Other hyponyms of chance event include hap, break, good luck, happy chance, coincidence, happenstance.

chance event (noun)	lottery (noun)
anything that happens suddenly or by chance without an apparent cause	players buy (or are given) chances and prizes are distributed by casting lots
	something that is regarded as a chance event