The second discontinuity experienced in the 1789 Communion Office for a worshipper familiar with the current prayer book is twofold; first, there a quite a number of elements placed in a different order from the present, and second, there are a few insertions we don’t have within our current rites. It’s easiest to present these changes in a chart:

By orienting the main liturgical elements by means of some common standard pieces, you can see where the dislocations occur. As you can see, both the 1928 and the 1979 American BCPs shift the service elements as both received input from successive waves of liturgical studies and theological shifts within the Anglican Communion and the Ecumenical Movement. I often remark that a lot of modern Episcopalians consider the 1928 BCP to be a very traditional book based on its use by traditionalists inside and outside of the Episcopal Church. However, it changed things in a number of ways and was fairly radical within the family of American BCPs. There is no doubt, however, that the 1979 BCP did bring some major changes driven by the Liturgical Renewal Movement and its ecumenical insistence on a return to 4th century ideals.
Here’s a version of the above chart that clearly marks the changes and when they appeared:

The first moving block shifts the Prayers of the People, the Exhortation, and the Confession & Absolution after the Offertory, functionally shifting it outside of the Communion Office proper. This movement elevates these prayers to be their own section, and, through juxtaposition, makes them a response to the readings and sermon within the Service of the Word
The second moving block–accomplished in the 1928 BCP–was the collecting of both the Lord’s Prayer and the Prayer of Humble Access after the Consecratory Canon and immediately before the Reception of the elements. This is an important theological change which I am going to put off describing because it will make much more sense when we get to our discussion of the sources of the 1789 BCP–so put a pin in that for the moment.
The third moving block is the yeeting of the Gloria in excelsis back to the beginning of the service. This current placement conforms to the classical place of the Gloria and, I suggest, undoes a key Calvinist theologically motivated structural move. Again, more on this in a later post.
There are a few new items that do not make this chart, focused as it is on the Communion Service Proper. The initial Lord’s Prayer will be a surprise to everyone, but the Ten Commandments will only surprise Rite II congregants as Rite I retains the option to use this in our present book. This is then followed by Christ’s Summary of the Law which is the Rite I either/or with the Decalogue. The concluding prayer to follow both the laws and commandments does not appear in our prayer book in either rite.
Within the Communion Office itself the main new item will be the Exhortation to Communion. There are three different Exhortations in the 1789 BCP: the first to be read the week before the Eucharist will be celebrated and warning the congregants who wish to receive to prepare themselves, the second to be used if the congregation is negligent in receiving the Eucharist, and the third–the one included in my post containing the text of the office–for use in the service where the Eucharist is being celebrated. For reference, large parishes would usually celebrate the Eucharist on the first Sunday of each Month and on Festivals (Christmas & Easter), smaller and country parishes would usually celebrate in quarterly, but there were regional variations that impacted this as well. Laity were expected to receive a minimum of 3 times a year. The 1928 BCP retained these three Exhortations, but moved them after the service as an optional item.
For most modern worshippers experiencing the 1789 service, the Exhortation will be a new experience. However it may not be or need not be… Our current book has an Exhortation on page 316-7 that can serve as a lead-in to Confession & Absolution with either the Penitential Office at the start of a service or in its traditional place between the Prayers of the People and the Confession & Absolution. (I will say, that I’ve never experienced it in all of my years of church-going though.)
So–that’s the second discontinuity between the 1789 Communion Office and the 1979 Book of Common Prayer, a reordering of elements and the inclusion of unfamiliar liturgical elements (even those that are retained though rarely used in the present book).