
Release 13 of Cinema 4D comes with a physical renderer that can handle some advanced render techniques better than the previous version. It’s not a replacement for the old one but an option – you have to decide wether it suits your needs for a given project. One thing it handles better is subsurface scattering, short SSS.
Wikipedia has a nice article, explaining what that does. In short, slightly translucent materials like skin, milk or porcelain transport light under its surface which scatters and exits at a different point.
The image above is a quick comparison of a material without and with the effect turned on. It’s not that the picture with SSS turned on looks more realistic per se, but it looks more sophisticated as a material in my opinion.