flame stitch vs sewing stitch

flame stitch and sewing stitch both are nouns.

Word	Noun	Adjective	Verb	Adverb
flame stitch	Yes	No	No	No
sewing stitch	Yes	No	No	No

As nouns, sewing stitch is a hypernym of flame stitch; that is, sewing stitch is a word with a broader meaning than flame stitch:

flame stitch: needlepoint embroidery stitch that produces zigzag lines
sewing stitch: a stitch made with thread and a threaded sewing needle through fabric or leather

Other hypernyms of flame stitch include embroidery stitch.

flame stitch (noun)	sewing stitch (noun)
needlepoint embroidery stitch that produces zigzag lines	a stitch made with thread and a threaded sewing needle through fabric or leather