Advent vs Second Coming

Advent and Second Coming both are nouns.

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

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

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

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

Advent (noun)	Second Coming (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