Price wise there about the same, however the specs do differ slightly. I am having trouble choosing between the 2. How big an advantage is having LED over LCD? Same for the brightness vs contrast ratio...
LED is just a matter of the backlight - some LCD monitors have Cold Cathode Fluorescent Lamps (CCFL) for the backlight, some have LEDs.
I doubt you'd need more than 240 cd/m2 in terms of brightness, and both monitors can provide that. The dynamic contrast ratio should be ignored, and I don't immediately find the static contrast ratio for either monitor.
The most significant difference I see in the specs is that the Acer offers DVI-D input, while the AOC is limited to D-Sub.
I don't think they're quite the same model numbers. For AOC, the F22S and F22S+ only have D-Sub, but the F22+ (note the missing S) has DVI-D as well. For Acer, the S221HQLbd only has DVI and D-Sub, but the S221HQLbid (note the added i) has HDMI as well.