Duncman's writeup here isn't 100% precise. "32 bits" are not used to specify the size of opcodes; in fact, many CPUs (including the popular x86 design) have variable-length opcodes.

"32 bit", in the Windows 95 marketing conspiracy meaning of the word, means that the operating environment supposedly is running in "true 32bit mode", which implies a direct 32 bit (4gb) memory addressing range, among other things. No more room to write, but look out for Win16MuTexes.