Unity uses a Scriptable Render Pipeline (SRP). This allows for high customizability. It offers two main pre-built pipelines: Universal Render Pipeline (URP) and High Definition Render Pipeline (HDRP).
Unreal Engine has a more unified, high-end rendering pipeline by default. It is built from the ground up to achieve high-quality visuals and photorealistic results compared to Unity’s HDRP. It is renowned for its ability to handle complex scenes and advanced features out of the box.
https://dev.epicgames.com/community/learning/tutorials/WbzD/unreal-engine-tip-15-unity-unreal-switching-rendering