Need help on denoising

Support Compositing and Post Processing
1

Hi,

I just want to know the differences between the different denoising options in Blender (2.91).
In the ‘Render properties’ I see following:

DNoise1

Under ‘View layer properies’ I see following:

DNoise2

And to make it even more complicated there are denosing nodes in the compositor.

Can anybody help me and tell me what’s the difference between those?

Thanks a lot!