We just have the Latin Mass in our area on the first and last Sundays of each month, plus every Wednesday morning at 7:00 am. So I go to the Novus Ordo Mass on the other Sundays. Aside from the Latin and the scala that helps us sing the Mass I found that there are four main differences.
1. The Latin Mass starts with Psalm 42 and the prayers at the foot of the Altar before the priest ascends the Altar.
2. The Latin Mass still uses the same readings year after year so some people still use the same Missal that they have been using for say 40 years.
3. The Last Gospel after Communion, John 1, "In the beginning was the Word, and the Word was with God, and the Word was God ..." I have read that the Last Gospel was added during the Albigensian heresy of the 1200s because heretics were infiltrating the Catholic priesthood and preaching heresy.
4. The prayers after a Low Mass, 3 Hail Mary's, Hail Holy Queen, St. Michael the Archangel prayer and Most Sacred Heart of Jesus ... Have mercy on us, 3 times.
The sung Low Latin Mass is beautiful. I believe it's called a Missa Cantata.
No.4 is not and has not been an official part of the Mass. That does not mean there is anything wrong with those prayers. Just that they are not, have never been and will probably never be an official part of the Mass.
Oh! and by the way similar to your No. 2, the readings in the Novus Ordo have been the same for 40 + years. All that has changed is the official translation used in English speaking countries. So someone who bought a Novus Ordo missal then could still be using it today at least as far as the readings are concerned..