lockstitch vs machine stitch

lockstitch and machine stitch both are nouns.

Word	Noun	Adjective	Verb	Adverb
lockstitch	Yes	No	No	No
machine stitch	Yes	No	No	No

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

lockstitch: machine stitch in which the top thread interlocks with the bobbin thread
machine stitch: a sewing stitch made by a sewing machine, sometimes using more than one thread

Other hypernyms of lockstitch include sewing-machine stitch.

lockstitch (noun)	machine stitch (noun)
machine stitch in which the top thread interlocks with the bobbin thread	a sewing stitch made by a sewing machine, sometimes using more than one thread