WAL file internals and why a 64 bit will not work on a 32 bit

I do know that WAL files taken from a 64 bit OS will not work on a 32
bit OS. However I have to prepare a technical answer to this.

That is, questions like - why a WAL file from 64 bit will not work in
32 bit. Also does the WAL file differ for same architecture but
different kind of partitions?

Regards
Dhaval