HD: High-Defenition. Pretty much every TV sold is now HD. You’d have a tough time finding one that’s not.
DLP & LCD Projection: These sets are the ones that sit on a table or floor. Usually about a foot deep. They don’t hang on a wall. The image is actually projected onto the screen from inside the TV. Oldest of the current technologies out there. Pros- Can get a really big screen for a cheap price. Cons- Inferior black levels, viewing angles, moving parts.
LCD vs. Plasma: Both are the common type you see hanging on walls. Thin.
Plasmas use more power and are heavier but have supposedly better black levels.
LCDs have less glare/reflections off the screen.
LED: Actually these are still LCD tvs. They just use LED backlighting. That’s supposed to give better black levels comparable to plasma. It’s the newest technology out there and you’ll pay for it.
Black Level: The better the black level a TV has the better contrast there is. TVs with a poor black level look washed out. Blacks look gray.