Can someone help me describe why I can tell when a game is made on Unity or Unreal within like 10s of seeing the visuals?

It's hard to describe but it's like there's a "Unity" look (usually flat/gradients, bright colors, fucking crystals everywhere) and a UE look.
I started rendering animations using Lumen and it's like... You have so much flexibility, yet every single UE game looks the same.