Ferdinand and Isabella vs Catholic Monarchs

Ferdinand and Isabella and Catholic Monarchs both are nouns.

Word	Noun	Adjective	Verb	Adverb
Ferdinand and Isabella	Yes	No	No	No
Catholic Monarchs	Yes	No	No	No

As nouns, Ferdinand and Isabella and Catholic Monarchs are synonyms defined as:

Ferdinand and Isabella and Catholic Monarchs: joint monarchs of Spain; Ferdinand V and Isabella I

Ferdinand and Isabella (noun)	Catholic Monarchs (noun)
joint monarchs of Spain; Ferdinand V and Isabella I	joint monarchs of Spain; Ferdinand V and Isabella I