detain vs slow down

detain and slow down both are verbs.

Word	Noun	Adjective	Verb	Adverb
detain	No	No	Yes	No
slow down	No	No	Yes	No

As verbs, slow down is a hypernym of detain; that is, slow down is a word with a broader meaning than detain:

Other hypernyms of detain include decelerate, retard, slow, slow up.

detain (verb)	slow down (verb)
cause to be slowed down or delayed	become less tense, rest, or take one's ease
stop or halt	lose velocity; move more slowly
deprive of freedom; take into confinement	become slow or slower
	reduce the speed of
	cause to proceed more slowly