speech rhythm vs inflection

speech rhythm and inflection both are nouns.

Word	Noun	Adjective	Verb	Adverb
speech rhythm	Yes	No	No	No
inflection	Yes	No	No	No

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

speech rhythm: the arrangement of spoken words alternating stressed and unstressed elements
inflection: the patterns of stress and intonation in a language

Other hypernyms of speech rhythm include guide, template, templet, prosody.

speech rhythm (noun)	inflection (noun)
the arrangement of spoken words alternating stressed and unstressed elements	the patterns of stress and intonation in a language
	a manner of speaking in which the loudness or pitch or tone of the voice is modified
	deviation from a straight or normal course
	a change in the form of a word (usually by adding a suffix) to indicate a change in its grammatical function