LTT had a great video on that. Basically Windows has a bug which sometimes prevents this sleep mode from working correctly and that nukes battery life. Microsoft has promised a fix, but apparently it's not resolved still. In theory it should work exactly the same as Power Nap. It sometimes does, but sometimes - not so much.
P.S. Power Nap used to be buggy as well, but Apple fixed it years ago.
Thanks for the details! When Power Nap was new I didn’t have a Mac that could use it. I think it used newer Intel tech than what my Mac had at the time IIRC.