HD stands for High Definition, HDTV is a HD TV. They can be Plasma, LCD(Liquid Crystal Display), TFT is Thin Film Technology, There are Rear Projection, and there are Projectors that use a screen. The quality can be limited by cable connection types. HDMI is very good, Component is less, S video and composite, among others.
Try:
Monster Cable Connection Guide - Home
and select cable type. good info.