clasp knife vs pocket knife

clasp knife and pocket knife both are nouns.

Word	Noun	Adjective	Verb	Adverb
clasp knife	Yes	No	No	No
pocket knife	Yes	No	No	No

As nouns, pocket knife is a hypernym of clasp knife; that is, pocket knife is a word with a broader meaning than clasp knife:

clasp knife: a large knife with one or more folding blades
pocket knife: a knife with a blade that folds into the handle; suitable for carrying in the pocket

Other hypernyms of clasp knife include pocketknife.

clasp knife (noun)	pocket knife (noun)
a large knife with one or more folding blades	a knife with a blade that folds into the handle; suitable for carrying in the pocket