I would have thought that for the TrueType Fonts setting within printer properties, the Download as Soft Font selection should have a different effect to the Substitute With Device Font selection.
Perhaps the Windows Font Substitution mechanism (see registry key HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\FontSubstitutes) is defining a font substitute for your font?
To check just what your driver is generating, you could (re-)print your file (preferably a small, sanitised data one), but choose the Print to File option in the Print dialogue.
Then analyse the resultant captured .prn file using the PRN File Analyse tool in the PCL Paraphernalia application, available via http://www.pclparaphernalia.eu
This should show whether a device resident font is being selected, or a soft-font is being downloaded.