reyes renderer also include ray tracers but they handle 3d data different.
renderman can even calculate the pixels of curves nurbs without breaking them down into polygones as far as i know.
the good thing about reyes is they are fast with displacements.
other renderer sucks in terms of speed and detail!
aqsis is also a kinda self made project. the support the api but do it their own way. no offense dudes!
Blender's renderer and external renderer export