What are the differences between diesel engines and gas ones?

Answer 1

The gas engine uses a spark to ignite the fuel. The diesel squeezes the air in the cylinder so tightly that it is hot enough to ignite the fuel without a spark.

That is basically the major difference.

The diesel engine typically has a compression ratio of 20 to 1 some go as high as 25 to 1. Gas engines normally have no more then a 9 to 1 ratio for normal driving. Race cars with a gas engine might go as high as 12.5 to 1 but they have to use very special fuel to prevent the gasoline from exploding too soon inside the engine and causing damage.

For an indepth explanation go to http://auto.howstuffworks.com/diesel1.htm

or http://en.wikipedia.org/wiki/Diesel_engine

Diesels tend to have more pulling power than a gas engine. They normally do not make good "hot rod" engines, but some turbocharged diesels can be very fast in a car or even in a truck.

Answer 2

diesel- more torque, more co2, more expensive, lower rev limit

gas- more hp, higher rev counter, better