open-class word vs content word

open-class word and content word both are nouns.

Word	Noun	Adjective	Verb	Adverb
open-class word	Yes	No	No	No
content word	Yes	No	No	No

As nouns, open-class word and content word are synonyms defined as:

open-class word and content word: a word to which an independent meaning can be assigned

open-class word (noun)	content word (noun)
a word to which an independent meaning can be assigned	a word to which an independent meaning can be assigned