On Windows they are significantly different; it's not just a matter of sharing a page of memory (though you certainly can do that if you want), because on Windo

On Windows they are significantly different; it's not just a matter of sharing a page of memory (though you certainly can do that if you want), because on Windows basically every kernel-provided cross-process object must be a fully securable kernel object that you can attach ACLs to, and the kernel has to be in the middle of operations to enforce those access controls (in order to conform to the old DoD TCSEC orange book requirements for mandatory access security).