The two most common styles of truck are "reverse" and "standard". Both designs offer different characteristics that change the feel of a board. These are easily told apart by looking at the kingpin (the bolt that holds the bushings).
The Sector 9 Static
These trucks have the kingpin sitting though the hanger. They are used for longboarding, downhill, carving, cruising, freeride, and freestyle. Reverse kingpin trucks sit lower and are more stable than standard trucks. They can fit on drop through or top mount decks.
The Rayne Catalyst
Standard trucks are for carving, cruising, tech sliding, and park. They are most commonly seen skateboarding, but have expanded into longboarding because of their agility. They sit higher and provide more control, but sacrifice stability. Because of their clearance and maneuverability, they fit top mount decks only.