This can be a bit confusing, and probably does not matter to most Catholics, but since these days are noted in the Liturgical Calendar, you might want to know the difference. In the Catholic Church’s liturgical calendar (Roman Rite), “memorial” and “feast” refer to specific ranks of celebrations, mainly for saints, mysteries of the faith, or events in the lives of Jesus and Mary. These ranks determine how prominently the day is observed in the Mass and Liturgy of the Hours, following the simplification after the Second Vatican Council.
There are three main ranks in descending order of importance:
1. Solemnity: (Highest Rank). Reserved for the most important celebrations, such as major events in Christ’s life (e.g., Christmas, Easter, Ascension, Corpus Christi), key Marian mysteries, and certain prominent saints (e.g., St. Joseph, Sts. Peter and Paul).
Liturgical elements: Gloria and Creed are recited; often has a vigil Mass the evening before; treated similarly to Sundays in precedence.
These are the “biggest” days.
2. Feast: (Middle Rank) Celebrates important saints (e.g., Apostles, Archangels, Evangelists) or lesser mysteries of the Lord or Mary (e.g., Transfiguration, Presentation of the Lord, Visitation).
Liturgical elements: The Gloria is said, but not the Creed. Proper prayers and readings are used, but it’s less elaborate than a solemnity.
Feasts have fixed dates and take precedence over most weekdays but yield to higher ranks like Sundays (except for Feasts of the Lord in some cases).
3. Memorial: (Lowest Rank)The most common way to honor most saints or certain aspects of the Lord/Mary.
These are further divided into two categories:
Obligatory Memorials (must be observed; marked with a capital M in calendars).
Optional Memorials (may be observed at the priest’s discretion; marked with a lowercase m).
Liturgical elements: No Gloria or Creed. The celebration is integrated into the weekday Mass with proper prayers/readings for the saint, but it’s simpler. Memorials can be overridden by higher-ranking days.