
This is a Disney (movie) character whose hair uses a particle system

This is a character in a video game that uses polygonal hair that uses texture + alpha to make it look realistic.
So why isn’t the hair of video game characters very realistic (compared to movies)?
Because video games use realtime rendering while movies are pre-rendered
This means that in video games, the more polygons per frame, the heavier the GPU work. If you use the particle system for hair then the game will be tough, no matter how advanced your commuter is. Meanwhile, pre-render is an animation that has been rendered beforehand and the output is in video format so that our computers don’t take up too much RAM.
Author: Yulianto Shark
Source: quora.com