It has been sugested here

http://websites.lib.ucr.edu/agnic/webber/Vol1/Chapter4.html

that they are indistinguishable: "While this variety can be traced back to the Azores, it seems unlikely that it originated there and probable that it came from Portugal. That likelihood has been greatly strengthened by the recent discovery there of an old variety that is indistinguishable from Valencia, which has been named Don João"

They are certanly similar, being the latest to produce here in Portugal, but the common strain known here as Dom João, produces more elongated fruits and the juice does not get the bad taste from oxidation when in contact with air...

Any thougts on this???

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