Well, as mentioned before by CyntrixTech:
#1 - Glossy Screen vs Anti-glare + 3H coating
#2 - No DVI Connection, only HDMI and VGA vs DVI + DP + VGA + 4 USB ports
#3 - No Height Adjustment + tilt vs Height-Adjustable stand, tilt + swivel + pivot
#4 - Slimmer
#5 - Edge to Edge Screen (almost)
#6 - 1ms faster than U series
#7 - Ultrasharp comes with Premium Panel Guarantee
#8 - Extra Power adapter vs one that Uses Build in Power Brick, easier for installation, less issues in arranging 3* power Bricks if yr getting it for Multi-monitor, and easier to maintain for office use (Bat.Backup), as it uses only 1 single cable.
#9 Brightness of  250 cd/m2 (typical)  VS 300 cd/m2 (typical)
U2312HM's features are highlighted in red. You choose your preference