What difference does it actually make to you? The graphics are sufficiently upgraded that it wouldn't change anything if they'd built the engine from scratch or overhauled it. Unreal Engine 4 is also built on UE3's framework. As are Cryengine 3 and Frostbite 3. Windows 8 is built from windows 7 which is built from windows vista and so on.
http://www.gamepur.com/feature/11148...-who-wins.html
I wouldn't say that at all. BF4 looks way better though.