In a nutshell:
The Byzantine Rite, consisting of 8 of the Eastern Catholic Churches, and of the Eastern Orthodox, is Generally:
- Using the Divine Liturgy according to St. John Chrysostom.
1.1) The liturgy is almost always sung, save for one prayer. The singing is usually active participation of the laity.
1.2) The liturgy is ad orientam with an Iconostas (wall of icons) separating the altar from the nave. (Think a communion rail, but floor to ceiling, and covered with holy images)
1.3) Traditionally, the people stand throughout
1.3.1) profound bows are made at various points where the Latins traditionally kneel.
1.3.2) Full prostration is the normative for adoration in Byzantine praxis; kneeling is a sign of remorse and horror, not adoration.
1.4) Ancient Liturgy: St. John’s liturgy is over a thousand years old; local adaptations vary
- Derived from the Constantinoplian tradition
2.1) difference in vestments
2.2) difference in holy days
2.3) difference in theology around the dogmas.
- at least 8 separate sets of Catholic Bishops, each separate, united under the Pope. The Largest is the Ukrainian Greek Catholic Church, under Cardinal Hussar. Each differs in tradition, but all share the same liturgies.
3.1) over 20 distinct Orthodox churches in the Eastern Orthodox Communion
3.2) A tradition of National churches, both Catholic and Orthodox
- Infants fully initated: Baptism, Confirmation, and First Communion typically 40 days after birth.
- Different secondary services
5.1) Adoration of the Blessed Sacrament is uncommon, and impractical. The Byzantine equivalent in tradition is usually restricted to the week after Easter, and is prostration before the tabernacle, revealed through the iconostas’s open royal doors.
5.2) Vespers, Matins, and Compline often done as public worship, not just as part of the office of the Hours; Canon Law requires them of the Eastern Churches before Sunday Divine Worship.
5.3) Differences in the wording of the common prayer, except the Our Father.
5.4) Sign of the Cross made right to left.
5.5) Veneration of Icons; lack of statuary.
It is important to note that the Byzantine liturgy is a valid catholic liturgy within the bounds of the Byzantine Rite Catholic Churches. If you want to learn more, it would best be taken to the Eastern Catholic Forum.
The Roman Church also exists in many places where kneeling is not customary for adoration, but for other, less liturgically appropriate states of mind. Hence, the GIRM does not specify kneeling as required, but allows it where not counter indicated.
All acts of divine worship within the Catholic Church may be appropriately done by standing with all due respect. But in All acts of Divine Worship via the Holy Sacrifice, the people of God are to conform to the local Catholic tradition. (That is buried in Canon Law. I’m not digging for citations right now.)
Kneeling during the consecration is normative to the US expression of the Roman Rite, but other traditions are “laudably retained”; there are two: kneeling throughout the eucharistic prayer, and standing throughout.
In the last paragraph of USCCB GIRM 43, the admonition is for the laity to follow the directives of the deacon, priest, or missal in use.
If the priest or the deacon says to stand, the GIRM backs him up in that case.