sales event vs selloff

sales event and selloff both are nouns.

Word	Noun	Adjective	Verb	Adverb
sales event	Yes	No	No	No
selloff	Yes	No	No	No

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

sales event: an occasion (usually brief) for buying at specially reduced prices
selloff: a sale of a relatively large number of assets (stocks or bonds or commodities) at a low price typically done to dispose of them rather than as normal trade

sales event (noun)	selloff (noun)
an occasion (usually brief) for buying at specially reduced prices	a sale of a relatively large number of assets (stocks or bonds or commodities) at a low price typically done to dispose of them rather than as normal trade