Y vs y

Y and y both are nouns.

Word	Noun	Adjective	Verb	Adverb
Y	Yes	No	No	No
y	Yes	No	No	No

As nouns, Y and y are synonyms defined as:

Other synonyms of Y include wye.

Y (noun)	y (noun)
the 25th letter of the Roman alphabet	the 25th letter of the Roman alphabet
a silvery metallic element that is common in rare-earth minerals; used in magnesium and aluminum alloys