The Win 95 = Mac 88 is about the user interface. I've already well-trashed pre-OS X cooperative multitasking and lack of memory protection, which was the reason for the stability problems.
But even that wasn't true. As someone who liked the taskbar, 95 and descendants was light years ahead of Mac. The Mac interface was no better than Windows 3.0, though I will admit the functionality was better. Apple did a better job tying the interface to the OS than Microsoft did (which really didn't happen until 95). So if you want to say Mac 88 = Windows 90 (3.0), even as far as the interface, be my guest. Anything later than that isn't accurate.