What is Passion?:
The usual meaning of passion is an aroused or intense emotion, but in the context of the Bible it is typically used to denote the suffering and death of Jesus. Thus we read in Christian literature about the Passion narratives or the Passion of Jesus. The only place in the Bible where the word is used this way is Acts 3:1, which refers to his Passion.
What is Passion Sunday?:
In the Christian liturgical calendar, Passion Sunday is the Sunday before Easter and thus the day launching Holy Week. This day was originally named Palm Sunday because it was the day Jesus entered Jerusalem, an event during which people laid palm fronds on Jesus path. Many churches have begun to use the term Passion Sunday to emphasize how Jesus entry into Jerusalem constitutes the beginning of the Passion narrative.