close vowel vs high vowel

close vowel and high vowel both are nouns.

Word	Noun	Adjective	Verb	Adverb
close vowel	Yes	No	No	No
high vowel	Yes	No	No	No

As nouns, close vowel and high vowel are synonyms defined as:

close vowel and high vowel: a vowel sound made with your tongue near the top of your mouth.

close vowel (noun)	high vowel (noun)
a vowel sound made with your tongue near the top of your mouth.	a vowel sound made with your tongue near the top of your mouth.