I know that APNG is an extension of PNG, while MNG is more of its own format (albeit developed by the original PNG developers). MNG is barely supported in any browser at all, while APNG almost only has native support in Firefox (for various backward compatibility- and decoding-related reasons, it seems).
Except all of these behind-the-scenes things, what are the differences between APNG and MNG? Does one have features the other doesn't (for example, storing only parts that are modified instead of always whole frames)? Does one have better performance or file size than the other?