That's not quite true. The Acer S231HLbid has an LED backlight and an HDMI input, so if either of those is important to you, go with that one. If you don't need either feature, I'd say go with the Acer G235HAbd, since it's cheaper by about $20 and has better reviews at NewEgg.
LCD monitors generally have either a Cold Cathode Fluorescent Lamp (CCFL) or an LED backlight. The LED backlight allows the monitor to be thinner, and reduces the power consumption. However, low-end LED-backlit monitors generally use a "white" LED, which according to Wikipedia is actually a blue LED with a yellow phosphor, which would explain the blue tinge I've read about in comparison with CCFL-backlit monitors. High-end LED-backlit monitors like the HP DreamColor LP2480zx or the Samsung SyncMaster XL30 (both of which have been discontinued, but cost $2000+ when they were still available) used red, green, and blue LEDs to produce a better white than CCFL backlights.
The only potential advantage I see to that one is the built-in speakers, but built-in speakers often have pathetic sound quality - to the point that a $20 set of separate speakers would sound better. Other than that, the specification aren't significantly different from the two you originally compared, and it's $10 more than the more expensive of those.