docking vs tying up

docking and tying up both are nouns.

Word	Noun	Adjective	Verb	Adverb
docking	Yes	No	No	No
tying up	Yes	No	No	No

As nouns, docking and tying up are synonyms defined as:

Other synonyms of docking include dockage, moorage.

docking (noun)	tying up (noun)
the act of securing an arriving vessel with ropes	the act of securing an arriving vessel with ropes