run up vs backstitch

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

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

As verbs, backstitch is a hyponym of run up; that is, backstitch is a word with a more specific, narrower meaning than run up:

run up (noun)	backstitch (noun)
	an overlapping stitch made by starting the next stitch at the middle of the preceding one

run up (verb)	backstitch (verb)
pile up (debts or scores)	do backstitches
raise by using ropes and pulleys
fasten by sewing; do needlework
make by sewing together quickly
accumulate, sometimes as a debt