tie down vs tie up

tie down and tie up both are verbs.

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

As verbs, tie down and tie up are synonyms defined as:

Other synonyms of tie down include bind, truss.

tie down (verb)	tie up (verb)
restrain from independence by an obligation	secure with or as if with ropes
secure with or as if with ropes	finish the last row
	restrain from moving or operating normally
	secure in or as if in a berth or dock
	invest so as to make unavailable for other purposes