The end-title (colophon) is composed of tail-piece (coronis or arabesque) and subscription. There is no real system in the different ornaments used for the colophons in Vaticanus. Obviously the scribe chose freely what to do.
Some observations:
The coronis is normally not reinforced. Exception: Acts.
In Matthew and Mark some red dots have been added later into the ornament.
Note the correction MATQAION for MAQQAION
Note the correction KOLOSSAEIS for KOLASSAEIS (From the facsimile it is also possible that the original read KOLLOSAIS.)
The same corrections appear at the titles. KOLOSSAI is the classical form and KOLASSAI the later popular form.
The ornament used for John is very beautiful. Probably meant to indicate the end of the Gospels.
For the Pauline letters the place of composition has been added later by another hand.
There is no ornament for Ephesians.
The "running spiral": only used for Romans. Scribe B avoids the running spiral. Skeat notes that scribe D of Sinaiticus has a lot in common with the scribes of Vaticanus, especially A. Both use the running spiral. The colophons resemble each other very much. In Sinaiticus the colophons of Tobit, Judith, Mark and 1. Thess. are by scribe D. For a comparison of the colophon Sinaiticus Mk and Vaticanus Deu, see below.
(Please note that due to the heavy compression the colours are not true to the original anymore.)