Compact Edition up until WinCE 6.0, then it became "Embedded Compact" with WEC7. Those who actually developed in WinCE/WEC7 should be familiar. Also a nod to those in the know: C:\WINCE600, C:\WINCE700. Platform Builder...
It's easy to pass this off as a nothingburger OS but it's actually a real RTOS with a performance kernel and priority scheduling. You can easily set the priority of a thread low enough (lower is higher priority) to starve critical OS threads like the worker thread for the file system, which is an incredible and useful amount of control in your hands. The device system and interrupt handling architecture are also very different from "big windows". Microsoft gives you most of the source code too and you build the OS image (NK.BIN) from source. WinCE/WEC7 is actually a pretty decent RTOS for doing Widnows-ish development on x86. I am by no means a MS fanboi but this was my favorite version of Windows to develop on and I'm sad to see it go.
It's worth noting that a lot of the hardware these OSs ran on did not get updated drivers for WEC2013 or IoT, so there is no effective migration path forward. If you produced a product with an older generation Intel graphics or NIC chipset then your product is effectively canceled with the suspension of WEC7 licenses.
Final thing I want to say about the WinCE family of OSs is that MS gave us _most_ of the source code but not all. I was able to customize the ATA driver to add ATA secure erase enhancements and also fix a bug in the USB host driver thanks to the open source, but guess where the remaining bugs in the operating system were :) The closed-source bits like the DHCP server and FAT filesystem driver still have outright bugs or performance issues because MS dropped support many years ago but refused to give customers access to enhance the software themselves. I think there's a lesson to be learned from that and I think WinCE could have continued to be a successful player with renewed support from MS and open access to the source code for paying customers. I'm sure it could make money, just not enough for them to care.