An OpenType font is always present if the font contains features that only exist in the OpenType specification but not in the TrueType specifications. These include, for example, a digital signature and OpenType features such as automatic ligatures.
This screenshot with the clear dual font preview has been made under Windows 7,
As you can see in the screenshot shot on Windows above, it is quite easy to visually compare fonts or typefaces for similarities or differences in this kind of presentation.
However, you can easily apply and use this solution to compare fonts and types without any hesitation for fonts comparison even on previous and current versions of Microsoft Windows 10 operating systems, regardless of whether the different fonts on a simple Domestic Windows desktop PC must be compared or to go on the tablet, Surface Pro / Go, or even on the MS server operating system.
It is a simple, yet effective tool to quickly and effectively scrutinize the fonts and typefaces, the font viewer was tested on various MS OS and successfully verified