It produces less noise because it uses way more noise reduction resulting is less detailed images.
Samsung camera app is still the best for quality and video smoothness.
Yeah comes down to preference in the end, personally I can't stand noise and try to reduce it as much as possible through lightroom despite losing some detail!

Really need to see the full size images though

What about when using normal mode as Samsung's HDR mode is generally much better than other OEM's HDR mode.
If you're rooted why don't you just restrict the permissions on the app?
Not rooted.