In what sense? The architecture between these two consoles is IMHO quite different.
Then again, Sega's main initial portwork was focused on the GameCube. The Dreamcast games Sonic Adventure 2, Ikaruga, Crazy Taxi, Phantasy Star Online and Skies of Arcadia were ported to the GameCube and not to the Xbox. They also brought originally-for-Dreamcast titles Super Monkey Ball, Beach Spikers and Billy Hatcher and the Giant Egg to the GameCube exclusively.
[1]: https://kotaku.com/how-xbox-could-have-helped-the-dreamcast-...
Super Monkey Ball was on the Xbox too. I was very happy when I discovered that, and even more so when it was playable on the X360.
> https://en.wikipedia.org/w/index.php?title=Windows_Embedded_...
"Unlike Windows Embedded Standard, which is based on Windows NT, Windows Embedded Compact uses a different hybrid kernel."
I am also pretty sure that Windows CE's architecture is quite different from the OS running on the XBox, but cannot give a quotable source on this. At least for the Xbox 360 and XBox One, I am pretty sure that I have read that their kernel is actually not so dissimilar from the kernel used in the NT line. The difference between the Windows NT line and the XBox 360/One OS rather lies in the software running above the kernel.
The OG Xbox kernel is an extremely heavily stripped down and modified Win2k kernel. No support for user mode, multiple address spaces, or more than one running process. No win32 in the kernel. USB, sound, and the vast majority of the graphics driver are statically linked into the process executable.