Noble steeds
In Mount&Blade: Napoleonic Wars there's a choice of three (or actually, four) types of horses. You have a choice of Light, medium and Heavy horses, with the honourable mention of the Artillery Train as a fourth type of horse.
Light horse:
The Light horses are the scout / hit-and-run-as-if-the-devil-himself-were-chasing-you type of horses. Light horses have very low health and are fairly easy to cut down, so beware when riding these horses. They make up for their lack of health with fair speed. Most scouting cavalry and light dragoons utilize the Light horses.
Medium horse:
The medium horse is the 'your average' horse. Medium maneuvrability, medium health threshold, medium speed. This horse is a good all-rounder, but doesn't excell in anything in particular. They are still very vulnerable to pikes and bayonets, so keep an eye out for those. The medium horse is the most seen horse on the battlefield, and most cavalry uses them.
Heavy horse:
The heavy horse lacks speed but makes up for it by having a sizable lifespan. They can survive pike and bayonet attacks, and are great for rushing head-on into an enemy line of infantry. The heavy horse is the horse of choice of all the Generals, as well as most Cuirass-class cavalry.
Honourable mention; The Artillery Train:
A fourth type of horse exists in Mount&Blade: Napoleonic Wars; being the Artillery Train. This particular horse is part of the Artillery regiments and spawns with a fixed carriage attached to the horse's saddle. People can limber cannons and howitzers onto this carriage, allowing transportation. Whilst these horses lack speed (the carriage prevents them from going any faster than plain walking speed), they have a high health threshold. Besides transporting artillery, they make good temporary defences to duck behind when your (artillery) division is under fire.
Light horse:
The Light horses are the scout / hit-and-run-as-if-the-devil-himself-were-chasing-you type of horses. Light horses have very low health and are fairly easy to cut down, so beware when riding these horses. They make up for their lack of health with fair speed. Most scouting cavalry and light dragoons utilize the Light horses.
Medium horse:
The medium horse is the 'your average' horse. Medium maneuvrability, medium health threshold, medium speed. This horse is a good all-rounder, but doesn't excell in anything in particular. They are still very vulnerable to pikes and bayonets, so keep an eye out for those. The medium horse is the most seen horse on the battlefield, and most cavalry uses them.
Heavy horse:
The heavy horse lacks speed but makes up for it by having a sizable lifespan. They can survive pike and bayonet attacks, and are great for rushing head-on into an enemy line of infantry. The heavy horse is the horse of choice of all the Generals, as well as most Cuirass-class cavalry.
Honourable mention; The Artillery Train:
A fourth type of horse exists in Mount&Blade: Napoleonic Wars; being the Artillery Train. This particular horse is part of the Artillery regiments and spawns with a fixed carriage attached to the horse's saddle. People can limber cannons and howitzers onto this carriage, allowing transportation. Whilst these horses lack speed (the carriage prevents them from going any faster than plain walking speed), they have a high health threshold. Besides transporting artillery, they make good temporary defences to duck behind when your (artillery) division is under fire.