Mechanics are a Specialization of both Engineer and Technician.
Depending on who is asked, the Mechanic is either the glue that holds everything together or the grease that makes it all go. Most Mechanics will tell you they do both, and then get back to work. The additional career skills of the Mechanic indicate the practical versatility, Brawl, Mechanics, Piloting (Space) and Skullduggery.
Mechanics can be found in both the Age of Rebellion Core Rulebook and the Edge of the Empire Core Rulebook.