I'm confused: they're saying the devices have an ARM A7 chip (presumably they mean Cortex-A7) in them, which is a full 32-bit microprocessor, but they're calling them "microcontrollers"? I would think Windows could run on a Cortex-A7, no? Perhaps the specific parts they're using have a ridiculously-low clock rate or other painful limitations?
You're right, but there is a lot of misunderstanding around this end of the market, mainly because advances have blurred the traditional segmentation. When talking about ARM, the 'M' in Cortex-M means 'microcontroller' whereas the 'A' in Cortex-A means 'application'. Cortex-A systems are often at the centre of 'System-on-Chips' and will run linux, and indeed the NT kernel as well, as they are bundled with enough RAM…
FWIW, my personal definition is "doesn't have an MMU"