Unity5 has some kind of global illumination library integrated if that is what you are referring to.
But as far as I know it is used to create lightmaps, But may also work dynamically to.
Both Unreal and Unity have "realtime GI" systems which sort of work under an extremely specific set of conditions, but they're not really a viable solution to lighting an entire game and pretty comparable to each other in terms of quality. Both can also bake static lightmaps and are pretty comparable in this regard as well.
I was thinking more about the visual compilation and look of the engines. Unity often looks jagged and artificial unless the game is 8 bit or modeled by a professional, something I haven't seen the new Unreal do.
Visually I feel like they're actually fairly comparable. It's probably a little bit easier to make an Unreal game look pretty quickly, but you can get both to look similarly good if you're willing to do a bit of math. It's also very easy to make either engine look terrible if you don't give it anything good to draw.