stammer vs speech disorder

stammer and speech disorder both are nouns.

Word	Noun	Adjective	Verb	Adverb
stammer	Yes	No	Yes	No
speech disorder	Yes	No	No	No

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

stammer: a speech disorder involving hesitations and involuntary repetitions of certain sounds
speech disorder: a disorder of oral speech

Other hypernyms of stammer include defect of speech, speech defect.

stammer (noun)	speech disorder (noun)
a speech disorder involving hesitations and involuntary repetitions of certain sounds	a disorder of oral speech

stammer (verb)	speech disorder (verb)
speak haltingly