sew together vs stitch

sew together is not a noun while stitch is a noun.

Word	Noun	Adjective	Verb	Adverb
sew together	No	No	Yes	No
stitch	Yes	No	Yes	No

As verbs, sew together and stitch are synonyms defined as:

Other synonyms of sew together include run up, sew.

sew together (noun)	stitch (noun)
	a link or loop or knot made by an implement in knitting, crocheting, embroidery, or sewing
	a sharp spasm of pain in the side resulting from running

sew together (verb)	stitch (verb)
fasten by sewing; do needlework	fasten by sewing; do needlework