knock off vs rip off

knock off and rip off both are verbs.

Word	Noun	Adjective	Verb	Adverb
knock off	No	No	Yes	No
rip off	No	No	Yes	No

As verbs, rip off is a hypernym of knock off; that is, rip off is a word with a broader meaning than knock off:

Other hypernyms of knock off include rip, steal.

knock off (verb)	rip off (verb)
stop pursuing or acting	remove by pulling or ripping violently and forcefully
get rid of (someone who may be a threat) by killing	take without the owner's consent
write quickly	deprive somebody of something by deceit
take by theft
cut the price of