To sum up things
Again both of these two monitors are almost identical
same resolution
same screen size (27 Inches)
same refresh rates
same response time
same viewing angle
same britness
same contrast ratio
BUT....
The ASUS monitor have a DVI-D input port that the DELL dosen't have while the DELL have two more USB 3.0 ports in its hub and a 1 x Audio line-out, 1 x Headphone port so you can use its built in speakers to listen to music or your in game sounds directly from your monitor without having to reach to the back of the case to plug in your headset which the ASUS monitor doesn't have