Windows 3.11, 95, and 98 are "32-bit hacks" written on top of 16-bit MS-DOS. The "32-bit" part of those operating systems is provided by a driver that, while it's still technically part of the operating system, does not result in a "true" 32-bit OS.
This is, in part, why "MS-DOS programs" don't run on any version of Windows after 98.
One of the main "lines in the sand" with Windows is whether the GDI is 16- or 32-bit. In a "real 32-bit" version of Windows (NT, 2000, XP, 2003 Server, Vista, etc.), the GDI is at least 32-bit. In WFW 3.11, Windows 95, and Windows 98, the GDI, like much of the rest of the OS, is 16-bit.