Yeah, but I think it's broken down into two parts (much like specular and diffuse lighting). Global illumination tends to refer to diffuse reflection, with the scattered diffuse light hitting nearby surfaces. And caustics referring to the bounce of specular highlights, with reflected light continuing on its reflected path…
Global illumination in the sense of radiosity is diffuse reflections. They're independent of the viewing angle. Rough surfaces will show radiosity but mirrors won't at all. Everything's reflections, but there's a difference between rough surface reflections and smooth surface, so we have diffuse and reflective surfaces in…
It's more like: It's all bouncing photons, with reflection only referring to a single surface and photons being reflected off it. GI is about light bouncing several times until its been diffused and absorbed enough. In real life specularity and GI exists as terms to explain things, they've never been 'this is how light…
Those differences mean that reflections are affected by the viewing angle, and GI is more diffused and the view angle doesn't change the lighting contribution. Isn't that the main difference we should take away? Also GI is mostly important when you have a direct light pointed at a surface, and reflections are generally…