Usually you can make it to more than one Carnival because Greek Orthodox follow the Julian calendar, while Catholics use the new, Gregorian, calendar. However, this year our calendars coincide.
Carnival is basically a time to many go wild right before the seriousness of the 40-day fast of Great Lent leading up to the Crucifixion of Christ on Good Friday and His Resurrection on Easter Sunday. Though it’s certainly tied to Orthodox Christianity, practicing Orthodox believers don’t participate in its more reckless aspects that are tied to Dionysus. The parades and floats, though? Those are fun!