Second Coming vs Advent

Second Coming and Advent both are nouns.

Word	Noun	Adjective	Verb	Adverb
Second Coming	Yes	No	No	No
Advent	Yes	No	No	No

As nouns, Second Coming and Advent are synonyms defined as:

Second Coming and Advent: (Christian theology) the reappearance of Jesus as judge for the Last Judgment

Other synonyms of Second Coming include Parousia, Second Advent, Second Coming of Christ.

Second Coming (noun)	Advent (noun)
(Christian theology) the reappearance of Jesus as judge for the Last Judgment	(Christian theology) the reappearance of Jesus as judge for the Last Judgment
	the season including the four Sundays preceding Christmas