Then there is no reason to differentiate, and one or the other would have been used - Why use both in the very same sentence?
The more likely sense is in the terminology of construction (as Christ is speaking of building a Church), wherein "petra" is the foundation, or possibly cornerstone, and "petros" is a building stone... a part of the wall.
There is no great difference between building stones. All are more or less the same thing. What is important is Peters confession that Jesus is the Christ. That describes the nature of the "building stones" which Christ will select to build with.
It is the fact that the confession is enabled by the Father - THAT is the salient point... There is no difference among Christ's followers.
That Peter was named is a special thing. For he was the first to confess his Lord. But he is only the first of many such building stones... those hardy stones which form the walls which hell cannot prevail against.
This silly succession nonsense should stop. It is futile, vain, and carnal. There were 120 disciples at Pentecost. It is unknown where all of the twelve went, not to mention the full 120. IF a laying on of hands is necessary to transmit some needful thing, how many times has such exponentially occurred from the hand of each and every one? God only knows... And that, it seems, is how He wants it (that none should boast).
Dollinger taught Church history as a Roman Catholic for 47 years in the 19th century and was one of the greatest and most influential historians in the Church of his day. He sums up the Eastern and Western understanding of Matthew 16 in the patristic period:
In the first three centuries, St. Irenaeus is the only writer who connects the superiority of the Roman Church with doctrine; but he places this superiority, rightly understood, only in its antiquity, its double apostolical origin, and in the circumstance of the pure tradition being guarded and maintained there through the constant concourse of the faithful from all countries.
Tertullian, Cyprian, Lactantius, know nothing of special Papal prerogative, or of any higher or supreme right of deciding in matter of doctrine.
In the writings of the Greek doctors, Eusebius, St. Athanasius, St. Basil the Great, the two Gregories, and St. Epiphanius, there is not one word of any prerogatives of the Roman bishop.
The most copious of the Greek Fathers, St. Chrysostom, is wholly silent on the subject, and so are the two Cyrils; equally silent are the Latins, Hilary, Pacian, Zeno, Lucifer, Sulpicius, and St. Ambrose.
St. Augustine has written more on the Church, its unity and authority, than all the other Fathers put together. Yet, from all his numerous works, filling ten folios, only one sentence, in one letter, can be quoted, where he says that the principality of the Apostolic Chair has always been in Romewhich could, of course, be said then with equal truth of Antioch, Jerusalem, and Alexandria.
Any reader of his Pastoral Letter to the separated Donatists on the Unity of the Church, must find it inexplicable...that in these seventyfive chapters there is not a single word on the necessity of communion with Rome as the centre of unity. He urges all sorts of arguments to show that the Donatists are bound to return to the Church, but of the Papal Chair, as one of them, he says not a word. We have a copious literature on the Christian sects and heresies of the first six centuriesIrenaeus, Hippolytus, Epiphanius, Philastrius, St. Augustine, and, later, Leontius and Timotheushave left us accounts of them to the number of eighty, but not a single one is reproached with rejecting the Popes authority in matters of faith.
All this is intelligible enough, if we look at the patristic interpretation of the words of Christ to St. Peter. Of all the Fathers who interpret these passages in the Gospels (Matt. xvi.18, John xxi.17), not a single one applies them to the Roman bishops as Peters successors. How many Fathers have busied themselves with these texts, yet not one of them whose commentaries we possessOrigen, Chrysostom, Hilary, Augustine, Cyril, Theodoret, and those whose interpretations are collected in catenashas dropped the faintest hint that the primacy of Rome is the consequence of the commission and promise to Peter!
Not one of them has explained the rock or foundation on which Christ would build His Church of the office given to Peter to be transmitted to his successors, but they understood by it either Christ Himself, or Peters confession of faith in Christ; often both together. Or else they thought Peter was the foundation equally with all the other Apostles, the twelve being together the foundationstones of the Church (Apoc. xxi.14).
http://www.christiantruth.com/articles/mt16.html
I was just thinking about this question last night. Is there some "official" list, and exhaustive, of who are considered "Church Fathers"? I have seen some references to some with their quotes and then in another place these very same people are called heretics. It is confusing. Since you seem to be very knowledgeable about history, do you have this list? Does it exist? Thanks!