They both feature very similar high-quality ah-ips panel with the same color gamut coverage. But that's where similarities end:
Dell is classic mid-class workstation monitor with professional look, great color-calibration software suite to use with X-Rite, best OSD menu on the market, stable height-adjustable base.
Asus is strange hybrid that doesn't really know what it wants to be. It has no height adjustability (big no for workstation), no VESA mount either, it has pointless 3W speakers, crap media features like dynamic contrast,etc..
Positives are aluminium chassis and thin bezel, but is that so important for working ?
Asus has been trying really hard to get into workstation/designer monitors but imho they still get it quite right. (including the rather good AsusArt series)