thirty-ninth vs 39th

thirty-ninth and 39th both are adjectives.

Word	Noun	Adjective	Verb	Adverb
thirty-ninth	No	Yes	No	No
39th	No	Yes	No	No

As adjectives, thirty-ninth and 39th are synonyms defined as:

thirty-ninth and 39th: the ordinal number of thirty-nine in counting order

thirty-ninth (adjective)	39th (adjective)
the ordinal number of thirty-nine in counting order	the ordinal number of thirty-nine in counting order