hundred-and-twenty-fifth vs 125th

hundred-and-twenty-fifth and 125th both are adjectives.

Word	Noun	Adjective	Verb	Adverb
hundred-and-twenty-fifth	No	Yes	No	No
125th	No	Yes	No	No

As adjectives, hundred-and-twenty-fifth and 125th are synonyms defined as:

hundred-and-twenty-fifth and 125th: the ordinal number of one hundred twenty-five in counting order

hundred-and-twenty-fifth (adjective)	125th (adjective)
the ordinal number of one hundred twenty-five in counting order	the ordinal number of one hundred twenty-five in counting order