The main difference is with the technology used in the panel -- cheaper panels (TN panels) generally only use 6 bits for each colour element of the display (Red, Green and Blue), meaning that it is capable of producing a much more limited range of colours (the thousands indicated by the article).
For playback purposes (DVDs, games, etc), most consumers won't notice the difference. For content creation, though, 6-bit panels are a disaster. I've seen cheap panels from Dell that simply could not display colours in the light blue or light yellow range correctly, and light greys not at all.
Wikipedia has an excellent article about the different types of LCD panels available, but the takeaway is basically "you get what you pay for."