link up vs link

link up is not a noun while link is a noun.

Word	Noun	Adjective	Verb	Adverb
link up	No	No	Yes	No
link	Yes	No	Yes	No

As verbs, link up and link are synonyms defined as:

Other synonyms of link up include associate, colligate, connect, relate, tie in.

As verbs, link up and link are synonyms defined as:

Other synonyms of link up include connect, tie.

As verbs, link up and link are synonyms defined as:

Other synonyms of link up include connect, join, unite.

link up (noun)	link (noun)
	a fastener that serves to join or connect
	a two-way radio communication system (usually microwave); part of a more extensive telecommunication network
	an interconnecting circuit between two or more locations for the purpose of transmitting and receiving data
	a channel for communication between groups
	(computing) an instruction that connects one part of a program or an element on a list to another program or list
	a unit of length equal to 1/100 of a chain
	the means of connection between things linked in series
	a connecting shape
	the state of being connected

link up (verb)	link (verb)
make a logical or causal connection	make a logical or causal connection
connect, fasten, or put together two or more pieces	connect, fasten, or put together two or more pieces
be or become joined or united or linked	link with or as with a yoke
	be or become joined or united or linked