🏁 Off can mean how something is done, as in falling off a cliff. Of can be a word you use with a verb, as in I know of a way to get there quicker:
I know of a boy who has fallen off a pier into the sea.
If they don’t get control of this crowd, it’s all going to kick off!
Of course you can’t put your feet on the sofa!
🎯 💻 Want to try a test?
🚦We can also use of informally to show belonging if we don’t want to use an apostrophe:
That car of Chloe’s needs a wash!
🎓 Of is a word called a preposition and it’s often used to show a relation between words, like in ‘know of’ and ‘control of’ below. The word off is usually an adverb to describe how something is being done, e.g. fallen off (instead of fallen under, fallen into, fallen through and so on). It can also be part of a noun like playoff, takeoff and so on (these words can also be hyphenated).