happy chance vs fortuity

happy chance and fortuity both are nouns.

Word	Noun	Adjective	Verb	Adverb
happy chance	Yes	No	No	No
fortuity	Yes	No	No	No

As nouns, fortuity is a hypernym of happy chance; that is, fortuity is a word with a broader meaning than happy chance:

happy chance: an unexpected piece of good luck
fortuity: anything that happens suddenly or by chance without an apparent cause

Other hypernyms of happy chance include accident, chance event, stroke.

happy chance (noun)	fortuity (noun)
an unexpected piece of good luck	anything that happens suddenly or by chance without an apparent cause