Scan Rate:
The scan rate is in direct correlation to number of lines drawn on the tube. These lines are "drawn" by an electron gun inside the tube.

The scan rate determines the vertical resolution.

Bandwidth:
Basically the higher the bandwidth the sharper the picture. Now we're getting really technical, huh?

The band width determines horizontal resolution and is stated in lines-per-inch.

There are several different types of "signals" available for home theatre.

RGB Video:
The cream of the crop in terms of picture quality, but of course RGB Video is also the most expensive and is only available in very high end large screen projection TV's.

Composite Video:
This is the most common type, which basically breaks the image into two segments, brightness and color.

S-Video:
Offered on higher home theatre units is the next step up from composite.

Component Video:
The newest kind on the block, component video was made to improve on S-video. It separates the video three ways,
Y/R -- luminance and red,
Y/B -- luminance and blue
Y -- luminance channel only.
Component Video's quality is second only to RGB.

For more information on the different types of TV's click here.