49th vs forty-ninth

49th and forty-ninth both are adjectives.

Word	Noun	Adjective	Verb	Adverb
49th	No	Yes	No	No
forty-ninth	No	Yes	No	No

As adjectives, 49th and forty-ninth are synonyms defined as:

49th and forty-ninth: the ordinal number of forty-nine in counting order

49th (adjective)	forty-ninth (adjective)
the ordinal number of forty-nine in counting order	the ordinal number of forty-nine in counting order