short vowel vs vowel sound

short vowel and vowel sound both are nouns.

Word	Noun	Adjective	Verb	Adverb
short vowel	Yes	No	No	No
vowel sound	Yes	No	No	No

As nouns, vowel sound is a hypernym of short vowel; that is, vowel sound is a word with a broader meaning than short vowel:

short vowel: In languages that distinguish vowel length, a vowel which is normally pronounced shorter than a long vowel.
vowel sound: a speech sound made with the vocal tract open

Other hypernyms of short vowel include vowel.

short vowel (noun)	vowel sound (noun)
In languages that distinguish vowel length, a vowel which is normally pronounced shorter than a long vowel.	a speech sound made with the vocal tract open