Saint Christopher vs St. Kitts

Saint Christopher and St. Kitts both are nouns.

Word	Noun	Adjective	Verb	Adverb
Saint Christopher	Yes	No	No	No
St. Kitts	Yes	No	No	No

As nouns, Saint Christopher and St. Kitts are synonyms defined as:

Saint Christopher and St. Kitts: the largest of the islands comprising Saint Christopher-Nevis

Other synonyms of Saint Christopher include Saint Kitts, St. Christopher.

Saint Christopher (noun)	St. Kitts (noun)
the largest of the islands comprising Saint Christopher-Nevis	the largest of the islands comprising Saint Christopher-Nevis
Christian martyr and patron saint of travellers (3rd century)