Reference

In the 1969 revision of the Roman Catholic liturgical calendar, feast days were categorized into three main types: solemnities, feasts, and memorials. Each of these has a different level of importance and is celebrated differently within the liturgy.

1. Solemnities: These are the highest-ranking liturgical celebrations. They commemorate the most significant events in the Christian faith, such as Easter and Christmas, or honor important saints. Solemnities often include the recitation of the Gloria and the Creed during Mass, and they may also have a vigil Mass the evening before. If a solemnity falls on a Sunday, it takes precedence over the regular Sunday liturgy.

2. Feasts: These are of lesser importance than solemnities but still hold significant liturgical weight. Feasts typically celebrate events in the life of Jesus, Mary, and the apostles. The Gloria is recited during Mass on feast days, but the Creed is not. Unlike solemnities, feasts do not usually have a vigil Mass.

3. Memorials: These are the lowest-ranking liturgical celebrations and are primarily dedicated to the saints. Memorials can be either obligatory or optional. On these days, the Gloria is not recited, and the liturgy is generally simpler compared to solemnities and feasts.

The distinctions among these categories reflect their importance and are marked by specific liturgical elements. For more detailed information, you can refer to resources like Wikipedia or Catholic Online.