Hi Philipp1980,
unfortunately, in this moment, you can only download a demo of the new R20, and there is not a c4doctane demo version for R20 currently, but as soon as it will be available, you can download and install both demo versions and try by yourself the differences between 3ds Max and C4D workflow.
C4D has its own instances system, and c4doctane can use it and also has a special Scatter object.
There are oobviosly different plugins from max, like Forester, instead of Forest Pack, or X-Particles and Turbulance FX, instead of PhenixFD or Fume, for example.
From the octane plugin side, c4doctane is the best integrated plugin, in my opinion

ciao Beppe