What makes a diesel engine different to a regular gas engine, and is one better than the other?

Any certified gearhead knows that diesel engines do not use spark plugs. But why not? If power in an engine is created by combustion or explosion of flammable liquids, won't a spark plug in a diesel ...

The LBZ variant of the Duramax from the 2006/2007 Chevy Silverado and GMC Sierra pickups is one of the most well-loved diesel engines by Chevy fans.