bet on vs parlay

bet on is not a noun while parlay is a noun.

Word	Noun	Adjective	Verb	Adverb
bet on	No	No	Yes	No
parlay	Yes	No	Yes	No

As verbs, parlay is a hyponym of bet on; that is, parlay is a word with a more specific, narrower meaning than bet on:

Other hyponyms of bet on include ante, double up.

bet on (noun)	parlay (noun)
	a series of wagers in which the winnings from one wager are used as a stake for the subsequent wagers

bet on (verb)	parlay (verb)
place a bet on	stake winnings from one bet on a subsequent wager