In what way does the contrast makes a difference?

"Basically contrast is the measure of the difference between pure black (#000000, if we were talking in hex codes) and pure white (#FFFFFF).

The larger the contrast the more values between these two extremes that can be displayed, so you'll get better discrimination between colours. You'd definitely want a high contrast monitor if you were doing a lot of photo manipulation and video editing. You might even want one for gaming.

So the second monitor has better contrast, though this shouldn't be the only thing you use to choose between the two."

"The specs are important, but the lesson I've learned (having been burned many times in the past) is don't trust the manufacturer. Go see the monitors, on and in use, yourself. Check out the colors, the white, the black, the grays and especially the tans. (The tans always give away a bad monitor -- bad monitors display tan as gray.)

Certainly, given the two you're interested in, I'd go with the 15000:1. But I try not to buy monitors sight-unseen anymore. Remember -- the better your screen, the easier on your eyes."