Unreal Engine 4 is much much newer than Unity…what are you talking about?
UE4 was completely rebuilt. It is not UDK rehashed. It’s 2 years old. I have also heard that every major release of UE4 is rebuilt and refactored piece by piece to keep all of the code clean…i cannot confirm this though. I have also heard that Unity source code is a complete mess.
Unity GI isn’t even usable. It’s clunky as hell and some are even calling it a step back from Beast. Even with GI, Unity still cannot touch UE4 in lighting and you drop 20fps or more using the exact same scene between UE4 and Unity…why is that?