tie up vs tie down

tie up and tie down both are verbs.

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

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

Other synonyms of tie up include bind, truss.

tie up (verb)	tie down (verb)
secure with or as if with ropes	restrain from independence by an obligation
finish the last row	secure with or as if with ropes
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