front vowel vs vowel

front vowel and vowel both are nouns.

Word	Noun	Adjective	Verb	Adverb
front vowel	Yes	No	No	No
vowel	Yes	No	No	No

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

front vowel: (phonetics) Any vowel sound produced in the front of the mouth.
vowel: a speech sound made with the vocal tract open

Other hypernyms of front vowel include vowel sound.

front vowel (noun)	vowel (noun)
(phonetics) Any vowel sound produced in the front of the mouth.	a speech sound made with the vocal tract open
	a letter of the alphabet standing for a spoken vowel