Passion Sunday is better known as Palm Sunday.

Passion Sunday is also called Palm Sunday.

Prior to Vatican II the fifth Sunday of Lent was known as Passion Sunday. However, in 1969 Pope Paul VI combined Passion Sunday with the 6th Sunday of Lent - Palm Sunday.

In the Roman Catholic Church, before 1960 the Fifth Sunday of Lent was called Passion Sunday because the (lengthy) Passion of the Lord was read at Mass as the Gospel reading. In 1960, Blessed Pope John XXIII changed the name of Passion Sunday to "First Sunday of Passion-tide," to conform to what Pope Pius XII had done earlier--he had changed the name of Palm Sunday to "Second Sunday of Passion-tide, or Palm Sunday." That lasted until 1969 when Pope Paul VI abolished Passion-tide (as a sort of sub-season of Lent), so as of right now the Sunday before Palm Sunday is officially known as the Fifth Sunday of Lent.

But--I suspect many people would know what you are talking about when you say "Passion Sunday", particularly old-fashioned or Traditional Roman Catholics and very high-church Episcopalians