Sorry to ask this rather obscure Q but ST "engineering" is not really contactable via any normal means...
It looks like a superset in every way, comparing the data sheets.
They even made the 2MB of flash in the 437 as two 1MB banks, which rather defeats the point of having 2MB unless you can generate "large model" code like one used to do with the old Z80 etc if wanting to have > 64k of code. It's really naff. It likely limits the usage of the extra 1MB to storing copies of backup (known working) firmware, and such like.