A modern mustang only have two options between the main production engines. 2.3L EcoBoost turbocharged four-cylinder which is 315 horsepower or a 5.0L Coyote V8 which is 480 to 500 horsepower. The most common is a 2.3L EcoBoost because of the lower cost and higher volume engine. The biggest differences are the Eco Boost is better for the fuel economy, its lighter, and its cheaper while the Coyote V8 is much quicker, and has an excellent mod potential. People who like Mustangs prefer the Coyote V because of its sound, performance, and the modification potential.
This image above is the 5.0L Coyote V8 engine
This image is th 2.3L EcoBoost