For the uninitiated: LCD stands for Liquid Crystal Display while plasma stands for a screen filled with gases (neon or xenon, take your pick). You can learn more on this particular topic LabRats Episode #18.
Both technologies come in flat-panel screens. The pictures that you see consist of pixels. Each pixel contains all three basic colors: red, green and blue. This is called a picture element. Abbreviated: a pixel. The deal behind a plasma screen picture rendition is when to turn the different color elements within individual pixels on and off, in which order and how strongly and intensively.
Plasma screens provide very vibrant colors, but they tend to use more energy than LCD. These screens, of course, are on par here, except LCD is using liquid crystal to achieve the same effect. With LCD screens, the technology is at least as much involved, but Sean and Andy demonstrate it in its basic, easy-to-understand form.