I'm not sure what you mean here?
These are both the CDC defined metrics. One they've been using for months (and still are for health care facilities) and one that's been around for the last couple of months (maybe less, time is hard to judge these days).
If the question is how did they determine the cut offs between each level? I've got no idea, they could have pulled them out of thin air. Presumably if they did just make them up out of thin air, it was done by people with the knowledge and expertise to make that kind of determination. I would assume a little more went into it though, with some work done based on impacts and goals.
Comparing the two, you can judge them on how they work differently compared to each other. Not so much on how those cut offs work in an absolute sense.
CDC Landing Page:
CDC’s home for COVID-19 data. Visualizations, graphs, and data in one easy-to-use website.
covid.cdc.gov
There's links at the top to both, with more links and links and then even more describing both of them.