papist vs Roman

papist and Roman both are nouns.

Word	Noun	Adjective	Verb	Adverb
papist	Yes	Yes	No	No
Roman	Yes	Yes	No	No

As adjectives, papist and Roman are synonyms defined as:

Other synonyms of papist include papistic, papistical, popish, R.C., Roman Catholic, Romanist, romish.

papist (noun)	Roman (noun)
an offensive term for Roman Catholics; originally, a Roman Catholic who was a strong advocate of the papacy	a resident of modern Rome
	an inhabitant of the ancient Roman Empire

papist (adjective)	Roman (adjective)
of or relating to or supporting Romanism	of or relating to or supporting Romanism
	of or relating to or derived from Rome (especially ancient Rome)
	characteristic of the modern type that most directly represents the type used in ancient Roman inscriptions