If you would like to go in depth about all the changes, there is an excellent book called “From Breviary to Liturgy of the Hours” which chronicles the change. There are many many changes, big and small, way more than in this post.
The main change was a shortening of the “hours” (i.e. Matins, Lauds, Vespers, etc. ) to more or less equal length. Since the time of St. Pius X, the outline of the breviary was as follows (for simplicity sake, I’ll omit the breviary changes of John XXIII which were only in place for less than a decade)
The old breviary used to cover all the psalms in a week. The LOTH does it in 4 weeks and omits certain psalm verses which have an imprecatory character.
Beginning of the hours
Until 1956, all the hours , except during Triduum (Maundy Thursday to Holy Saturday) and the Office of the Dead, began with either the
Triple Prayer or the
Dual Prayer.
The Triple prayer said before Matins and Prime (and after Compline) was the Our Father, the Hail Mary and the Creed. Before beginning any of the other hours, the Dual Prayer- Our Father and Hail Mary- were said. This was like a kind of preparatory prayer before the beginning proper.
All the hours (except Matins) began with the opening versicles as they still do. “O God come to my aid”, etc. The difference between the breviary and the LOTH is that the breviary had instead of Alleluia in Lent “Praise to you O Lord King of eternal glory.” In the LOTH of the hours, Alleluia is omitted in Lent and not replaced with anything.
Matins began as it begins in the LOTH “Lord open my lips, etc.” but unlike the LOTH it was followed by “O God come to my aid, etc.” as well
After that, this is the format of the breviary hours.
Lauds and Vespers
5 psalms + antiphons
Scripture Reading
Hymn
Verse and Response
Canticle of Zechariah/Mary (Benedictus/Magnificat) with its antiphons
On the more penitential days, a series of intercessory petitions called the
preces were said
Collect (Closing Prayer)
Commemorations *
Closing versicles. These were
V. The Lord be with you. R. And with your spirit. [laypeople: O Lord hear my prayer. And let my cry come unto you]
V. Let us bless the Lord R. Thanks be to God.
V. May the souls of the faithful departed, through the mercy of God, rest in peace. R. Amen.
Until 1956 this was followed by:
Our Father and the verse:
V. The Lord grant us his peace. R. And eternal life. Amen.
Then was sung an antiphon of the BVM Mary according to the season. In the LOTH, this is only sung after Compline (Night Prayer). This was followed by a verse, response and collect in honour of the BVM.
Then was said “May the divine assistance remain with us always. Amen.”
- Commemorations was what was usually done when two feast days overlapped. The lesser one was remembered at the end by a commemoration., Today in the LOTH, i that ahppens, the lesser feast is omitted.
At Lauds and Vespers a commemoration was made by saying the Benedictus/ Magnificat antiphon, the Verse and Response and the Closing Prayer of the feast being commemorated.
e.g. if I am commemorating the Holy Cross since it overlaps with the Seven Sorrows. I will say Vespers of the Seven Sorrows. At the end, I will say
Magnificat Ant. O blessed Cross, you alone were found worthy to bear the Lord and King of heaven
V. This sign of the Cross shall be in heaven.
R. When the Lord shall come to judgement.
Let us pray. O God, who on this day makes us glad by the yearly feast of the Exaltation of the holy Cross : grant, we beseech you, that we who have on earth acknowledged the mystery of redemption, may rejoice in its everlasting rewards in heaven. Through the same our Lord Jesus Christ…….
Until 1956, there was also something called a Common Commemoration. On some days when no feast was celebrated, or for lower ranking saints, then a commemoration was said to remember all the saints and the BVM.
Ant. May the blessed Mother of God, the Virgin Mary and all the Saints, intercede for us with the Lord
V. The Lord has glorified his saints
R. He has heard their crying to him
Let us pray. Defend us, O Lord, we beseech you, from all dangers of mind and body : and at the intercession of the blessed and glorious ever-Virgin Mary, Mother of God, of blessed Joseph, of your holy Apostles Peter and Paul, of blessed N., [insert patron of church] and of all your Saints, mercifully grant us health and peace; that all troubles and errors being destroyed, your Church may serve you in secure freedom Through the same.
our Lord Jesus Christ…….
Please ask if something is unclear