It's not a comparison, but if you're looking for a lightweight RTOS and trying to decide between the two Zephyr looks appealing at first because you think you'r

It's not a comparison, but if you're looking for a lightweight RTOS and trying to decide between the two Zephyr looks appealing at first because you think you're getting a lot of facilities that are equivalent to a Linux-class kernel. And then you discover you're not getting any of that. If all Zephyr DT is doing is making a fancy header file for me, I'd rather just build my own and skip the learning curve.