This refers to how reactions to violent acts are portrayed.
Unrealistic
Characters react to violence in a way that is not representative of real life, such as by disappearing or by being so small as to obscure what is happening. The key is the reaction to violent action. If a realistically depicted character reacts to violence in an exaggerated or nonsensical way, this would still be considered an unrealistic portrayal of violence despite the fact that the character may appear "photorealistic" in depiction.
Realistic
Depictions of violence where the character reacts as it would in real life or descriptions of violence in a real-world setting. Portrayals that are realistic in nature, even if they include fantasy or non-human characters (including aliens, animals, and robots), should be considered realistic.