Passiontide

Passiontide in the Current Liturgical Calendar

Since the revision of the Catholic liturgical calendar in 1969, Passiontide has been synonymous with Holy Week. Palm Sunday, the final Sunday before Easter, is now known as Passion Sunday, though in practice it is almost always referred to by its former name. (Sometimes you may see it listed as Passion (Palm) Sunday, reflecting the current usage.)

The Traditional Period of Passiontide

Before the revision of the liturgical calendar, however, Passiontide was the period of Lent that commemorates the increasing revelation of Christ's divinity and His movement toward Jerusalem. Holy Week was the second week of Passiontide, which began with the Fifth Sunday in Lent, which was known as Passion Sunday. (The Fifth Week of Lent was likewise known as Passion Week.) Thus Passion Sunday and Palm Sunday were (unlike today) separate celebrations.
The revised calendar is used in the Ordinary Form of the Mass (the Novus Ordus), which is the form of the Mass celebrated in most parishes.