Windows 10 is a huge redesign and a facelift to the older versions, even against Windows 8.1. If you look at the new UI you can get the idea that there were very different designer teams at work because nothing looks uniform or consistent. Here is the gallery of ridiculousness...
Win-X shortcut menu for the control panel
Though I use the default fonts and sizes some applications are rendered differently. It seems they do not work well in Windows 10:
Taskbar context menu and single task context menu (from the taskbar):
Windows Apps look also different and sometimes an addtional button is worth nothing:
Hey, a "..." button - must be something more behind it!
Erm... nope, it isn't.
Serverity: harmless but annoying