All of those flat-panel monitors use LCD (liquid crystal display) panels. The difference is the lamps that provide the backlight that shines through the LCD.
These lamps are either compact fluorescent lamps (CFL) or light emitting diodes (LED). CFL may provide a better color spectrum than some LEDs. LEDs use less energy (and therefore generate less heat) and can allow monitors to be built thinner and lighter than with CFLs.
The end user will notice a much larger difference in LCD monitors based on the LCD panel type used - twisted nematic (TN), in-plane switching (IPS) or patterned/modified vertical alignment (PVA or MVA). TN LCD panels are the fastest and cheapest, but they do a poor job with color accuracy and they suffer horrible changes in brightness and hue when viewed from any angle other than perpendicular to the screen. IPS panels have much better color accuracy and the best viewing angles. PVA/MVA panels are the slowest. Color accuracy, black levels and viewing angles are good.
i7-2600K, H70, P8P67-M Pro, 16 GiB, HD7950, SSD, 3 HD, Blu-ray, X-Fi Ti Pro, Antec P182, S75CF, 3007WFP+2001FP, RK-9000BR, MX518
i5-3570K, GeminII-S524, P8Z77-M Pro, 16 GiB, HD7770, SSD, 2 HD, Blu-ray, InifiniTV4, NSK2480, 55" TV; Asus UX32VD