run up vs join

run up is not a noun while join is a noun.

Word	Noun	Adjective	Verb	Adverb
run up	No	No	Yes	No
join	Yes	No	Yes	No

run up (noun)	join (noun)
	a set containing all and only the members of two or more given sets
	the shape or manner in which things come together and a connection is made

run up (verb)	join (verb)
pile up (debts or scores)	make contact or come together
raise by using ropes and pulleys	cause to become joined or linked
fasten by sewing; do needlework	become part of; become a member of a group or organization
make by sewing together quickly	come into the company of
accumulate, sometimes as a debt	be or become joined or united or linked