how splwow64 works

Hi, in the WDK documentation, it says that,

"Limitations on Device Context Handles
If a 32-bit application is running on a 64-bit version of the Microsoft
Windows operating system, a printer driver plug-in that is running in the
context of the Splwow64.exe thunking process should not call the GDI
CreateDC function; this call will fail."

Does this mean that the 32-bit calls to GDI are not thunked up to 64-bit and
what the 64-bit programs eventually get is just a spool file of what
happened in 32-bit world?