The before picture is what is left after a masticator/brush mulcher goes through an area.
The machines leaving the nice tilled soil are the next step and often come through a year or more later after the wood has a chance to break down a little. They are closer to a road milling machine. The drums run hard carbide points that are not very sharp, but they are very wear resistant, allowing them to run in soil and even through rock.
Some mulchers can run down into the soil a little bit and leave a finer debris, but most of them are set up with sharp blades to process wood faster. Usually you want the woody debris to stay on the surface to prevent erosion and slow down regrowth of the brush. If you are turning overgrown brush into a farm field then you want to till in the woody debris and have it break down as quickly as possible.
One thing about the milling machine type tiller/mulchers is they burn a huge amount of fuel. One job I worked on the machine was running an 800 hp engine to drive the tiller. That thing was sucking off the fuel truck a couple times a day and I think it had a 300gal tank.
Hope that it explains it a little. The terms get blurred a little and different areas of the world call machines by different names so it can confuse things a bit.