knock-on effect vs consequence

knock-on effect and consequence both are nouns.

Word	Noun	Adjective	Verb	Adverb
knock-on effect	Yes	No	No	No
consequence	Yes	No	No	No

As nouns, consequence is a hypernym of knock-on effect; that is, consequence is a word with a broader meaning than knock-on effect:

knock-on effect: a secondary or incidental effect
consequence: a phenomenon that follows and is caused by some previous phenomenon

Other hypernyms of knock-on effect include effect, event, issue, outcome, result, upshot.

knock-on effect (noun)	consequence (noun)
a secondary or incidental effect	having important effects or influence
	the outcome of an event especially as relative to an individual
	a phenomenon that follows and is caused by some previous phenomenon