Win95 had preemptive multitasking. Win 3.1 had cooperative multitasking. The "multiuser" aspect of Win95 wasn't secure at all, it was more for letting multiple users have separated settings (e.g., browser bookmarks). However, even that often failed because software would assume a single user and store all the settings in a common location. Since there was no real security in FAT32 filesystems that was pretty easy to do.