system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: If games can render near photo-realistic graphics in real-time, why does 3D animation software (e.g Blender) take hours or even days to render simple animations?
gpt
Games use a lot of tricks to fake the photorealism at less cost than doing it for real (compressing textures, popins, etc.). The most important one is the lighting. You may notice that shadows don't always look right in games. You know how when you hold something colored under a light, it starts to glow that color? Games don't do this because they don't simulate the light for real, they change the textures to make shadows and light.

Real animation software takes no shortcuts and renders things with full textures and full detail. This software often calculates the path of each ray of light bouncing around the area until it runs out of steam. This calculation is what takes all the time because there are millions and millions of light rays to trace. 

Fun sidenote: a few weeks back, Nvidia managed to make real-time Ray tracing possible using some new technology they're developing, but so far it still take colossal amounts of power to run.