First Performance version - In 1880 the Finale was replaced by the one we know today. This was the version used in the first performance, conducted in February 20, 1881 by Hans Richter. Unpublished and unrecorded.
1881 version - Revisions were made just after the first performance, including a cut in the Andante and a nontrivial reworking of the Finale. This was the version played (with some cuts) at the second performance of the work on December 10, 1881 by Felix Mottl in Karlsruhe. Usually called "1878/1880" version. Published by Haas (1936). (In 1944 Haas prepared another edition, which is actually a mixture of the 1881 and 1878 versions).
He seems to be implying that the differences between the 1880 and 1881 versions are more than just negligible - though of course it all depends what you regard as "significant" and I'm in no position to judge.
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