open vowel vs low vowel

open vowel and low vowel both are nouns.

Word	Noun	Adjective	Verb	Adverb
open vowel	Yes	No	No	No
low vowel	Yes	No	No	No

As nouns, open vowel and low vowel are synonyms defined as:

open vowel and low vowel: a vowel that you pronounce with your tongue on the bottom of your mouth.

open vowel (noun)	low vowel (noun)
a vowel that you pronounce with your tongue on the bottom of your mouth.	a vowel that you pronounce with your tongue on the bottom of your mouth.