lisp vs speech defect

lisp and speech defect both are nouns.

Word	Noun	Adjective	Verb	Adverb
lisp	Yes	No	Yes	No
speech defect	Yes	No	No	No

As nouns, speech defect is a hypernym of lisp; that is, speech defect is a word with a broader meaning than lisp:

lisp: a speech defect that involves pronouncing `s' like voiceless `th' and `z' like voiced `th'
speech defect: a disorder of oral speech

Other hypernyms of lisp include defect of speech, speech disorder.

lisp (noun)	speech defect (noun)
a speech defect that involves pronouncing `s' like voiceless `th' and `z' like voiced `th'	a disorder of oral speech

lisp (verb)	speech defect (verb)
speak with a lisp