pontifical vs pompous

pontifical is a noun but pompous is not a noun.

Word	Noun	Adjective	Verb	Adverb
pontifical	Yes	Yes	No	No
pompous	No	Yes	No	No

As adjectives, pontifical and pompous are synonyms defined as:

Other synonyms of pontifical include grandiloquent, overblown, portentous.

pontifical (noun)	pompous (noun)
the vestments and other insignia of a pontiff (especially a bishop)

pontifical (adjective)	pompous (adjective)
denoting or governed by or relating to a bishop or bishops	characterized by pomp and ceremony and stately display
proceeding from or ordered by or subject to a pope or the papacy regarded as the successor of the Apostles	puffed up with vanity
puffed up with vanity