windfall profit vs net income

windfall profit and net income both are nouns.

Word	Noun	Adjective	Verb	Adverb
windfall profit	Yes	No	No	No
net income	Yes	No	No	No

As nouns, net income is a hypernym of windfall profit; that is, net income is a word with a broader meaning than windfall profit:

windfall profit: profit that occurs unexpectedly as a consequence of some event not controlled by those who profit from it
net income: the excess of revenues over outlays in a given period of time (including depreciation and other non-cash expenses)

Other hypernyms of windfall profit include earnings, lucre, net, net profit, profit, profits.

windfall profit (noun)	net income (noun)
profit that occurs unexpectedly as a consequence of some event not controlled by those who profit from it	the excess of revenues over outlays in a given period of time (including depreciation and other non-cash expenses)