Dodge is the brand of vehicle, while SXT denotes the specific exterior trim package of the vehicle. For instance, a 2014 Dodge Charger might come in SXT, SXT Plus or R/T. The differences between these lie mainly in the color choices and designs of various cosmetic features of the vehicle.
The abbreviation SXT means "Standard Extra," because it is close to the standard package of features with a few extra improvements. A Dodge SXT is similar to the base package found in many Dodge models, but these changes improve the appearance to add a luxury quality to the vehicle. A vehicle with the SXT package is able to have other options that the standard, or SE, package does not.