just because they are on the same os doesn't mean it's the same dpi-setting. in winecfg you can set up the dpi windows-programs will use, in linux you need to edit the configuration files for X and there set some dpi. wine does not automatically copy the system-wide settings, as far as I know in wine 96 is the default dpi no matter where...
and remember, in gui (especially in fonts) usually not the actual pixels are counted, instead it's the actual dpi-setting associated with those graphical elements. i.e. fixed-size fonts have the dpi-setting hardwired, gui-applications and TTF take the system-wide dpi settings...