Cycles is unbiased like Maxwell, Fry and Arion,
but the terminology for Material definitions
and its used parameters are slightly different
and you can use nodes for the material creation
as well, which Maxwell does not have.
Lighting wise there are no watt/lumen etc. presets/
settings for different lamp types in Cycles like Maxwell has,
nor a physically sun you can set the hours / day etc.
I think if you download Blender and play
with Cycles or Evee settings a bit you see
the differences compared to Arion and Fry.
while reading about lighting with Cycles and wondering about translating some things
from Maxwell i found this very interesting article for Cycles, explaining how to create
an accurate sun intensity model and using kelvin values for emitters via the blackbody
node. While not an add-on i think it could be very useful for some of us.
Just a minor remark: Cycles is not unbiased. The term unbiased is used for renderers that do no simplifications to speed up rendering. An unbiased renderer will have a minimal amount of settings and will always converge toward a result that is as realistic as possible.
Maxwell is an unbiased renderer, but Cycles is a biased renderer that uses methods to simplify the result in order to gain speed. This doesn't mean that Cycles is not a realistic renderer. V-Ray is also a biased renderer, and the physics math behind the light ray calculations is correct, but rendering is sped up by using methods like a light bounce limit, ray tresholds, blurring glossy reflections, noise reduction and other approximations that increase speed at the expense of realism. Using the right settings, a biased renderer can yield very similar results to an unbiased renderer while offering more speed.
The Blender 2.81 master builds now include Intel's AI-powered Open Image Denoiser (OIDN). It's quite impressive what it can already do with a one-sample rendering:
