RayTracing comes from the light source physics. RayCasting comes from the camera system. The former is for serious projects. The former was invented to make semi-advanced lighting in video game engines. This is why Unreal 5.4 is so amazing. It uses RTracing.
Hi Mark,
I'm afraid you are misinformed, or maybe I misunderstand you.
Both Ray Tracing and Ray Casting 'shoot' rays from the Camera.
I am not exactly sure about Ray Casting, but I believe it is something like Rasterization.
Cycles is a Path Tracer and Ray Tracing is like a 'faster version' of Path Tracing. Path Tracing is the most realistic, but also the slowest method. Ray Tracing can get pretty close to Path Tracing in result, but is a lot faster.