The major differences between the Traditional Missal (also known as the Tridentine Mass or the Extraordinary Form of the Roman Rite) and the New Missal (also known as the Ordinary Form of the Roman Rite) in the Catholic Church are as follows:

1. Language: The Traditional Missal is typically celebrated in Latin, while the New Missal is commonly celebrated in the vernacular language of the local region (e.g., English, Spanish, etc.). However, the Traditional Mass can also be celebrated in the vernacular with the permission of the local bishop.
2. Liturgical Form: The Traditional Missal follows the liturgical form codified by Pope St. Pius V after the Council of Trent in 1570, while the New Missal was promulgated by Pope Paul VI in 1969 as a result of the Second Vatican Council. The Traditional Missal retains the pre-Vatican II form, while the New Missal introduced significant changes to the liturgy.
3. Priest’s Position: In the Traditional Missal, the priest typically faces the altar, with his back to the congregation. This is commonly referred to as celebrating “ad orientem” (towards the east), symbolizing the orientation towards God. In the New Missal, the priest typically faces the congregation, celebrating “versus populum” (facing the people).
4. Structure and Prayers: The structure and prayers of the Mass differ between the two missals. The Traditional Missal follows a more elaborate and ritualistic form, with prayers and gestures that have been handed down over centuries. The New Missal simplifies some of the prayers and introduces new options for certain parts of the Mass. The overall structure remains similar, but there are differences in the arrangement of prayers and the inclusion of additional options.
5. Readings: In the Traditional Missal, the readings from the Epistle and Gospel are generally in Latin, and the readings themselves are usually prescribed for specific days. In the New Missal, the readings from the Epistle and Gospel are typically in the vernacular language, and a three-year cycle of readings is followed, allowing for a wider selection of biblical passages.

It’s important to note that both forms of the Mass are recognized and valid within the Catholic Church, and the choice between them is often a matter of personal preference or pastoral considerations. Pope Benedict XVI, in 2007, issued a document called “Summorum Pontificum,” which allowed for a wider celebration of the Traditional Missal within the Church, affirming its continued relevance and significance.