restrain vs tie up

restrain and tie up both are verbs.

Word	Noun	Adjective	Verb	Adverb
restrain	No	No	Yes	No
tie up	No	No	Yes	No

As verbs, tie up is a hyponym of restrain; that is, tie up is a word with a more specific, narrower meaning than restrain:

restrain: to close within bounds, or otherwise limit or deprive of free movement
tie up: secure with or as if with ropes

Other hyponyms of restrain include bind, tie down, truss, fetter, shackle, enchain, pinion, shackle, impound, pound, pound, pound up, fold, pen up, ground.

restrain (verb)	tie up (verb)
prevent the action or expression of	secure with or as if with ropes
to close within bounds, or otherwise limit or deprive of free movement	finish the last row
restrict (someone or something) so as to make free movement difficult	restrain from moving or operating normally
prevent (someone or something) from doing something	secure in or as if in a berth or dock
	invest so as to make unavailable for other purposes