forty-third vs 43rd

forty-third and 43rd both are adjectives.

Word	Noun	Adjective	Verb	Adverb
forty-third	No	Yes	No	No
43rd	No	Yes	No	No

As adjectives, forty-third and 43rd are synonyms defined as:

forty-third and 43rd: the ordinal number of forty-three in counting order

forty-third (adjective)	43rd (adjective)
the ordinal number of forty-three in counting order	the ordinal number of forty-three in counting order