quaternary vs 4th

quaternary is a noun but 4th is not a noun.

Word	Noun	Adjective	Verb	Adverb
quaternary	Yes	Yes	No	No
4th	No	Yes	No	No

As adjectives, quaternary and 4th are synonyms defined as:

quaternary and 4th: coming next after the third and just before the fifth in position or time or degree or magnitude

Other synonyms of quaternary include fourth.

quaternary (noun)	4th (noun)
the cardinal number that is the sum of three and one

quaternary (adjective)	4th (adjective)
consisting of or especially arranged in sets of four	coming next after the third and just before the fifth in position or time or degree or magnitude
coming next after the third and just before the fifth in position or time or degree or magnitude