Arrival and Advent denote in common the reaching of a destination.
Arrival implies precedent travel or movement.
- the arrival and departure of trains
- the morning of my arrival
Advent is sometimes applied to an important or even momentous arrival.
- look forward to the advent of the Messiah
Except when it connotes birth, it usually stresses appearance on the scene more than the coming or reaching of the end of a journey.
- life . . . with the advent of an attractive young woman took on acknowledged connotations of interest