Is it safe to fly with a B737-800? Is it different from a B737 Max 8?
All B737 Max, as of today 19-Sept-2019, are still grounded and will be for the foreseeable future. So if you are flying in an aircraft, you are guaranteed that it will not be one of those.

As for the underlying question "is it safe to fly in airplane model "X"?" the answer always is that if authorities are allowing it to fly, it is safe to the best of our knowledge.