Special Weapons and Tactics. Technically J's team has another acronym they go by, but it's the same thing. They are specifically trained for the types of cases that aren't routine police work. Too often that means they train for any and all situations in preparation for all the unknown factors.
For example, they can't possibly be prepared for the layout of every building floorplan in existence. Or for the great unknown of people in those aforementioned buildings. Where could they be, are they armed, are they dangerous, are they innocent, etc.
My brother is on the SWAT team for his county too, so sometimes it's interesting for the two to compare the differences in their training approach.
A particular situation that comes to mind is when they serve a warrant on a meth lab. The sheer volatility of these labs is such that the team is forced to rethink their approach, and severely reduces or eliminates a number of the tools they typically rely on. No flash-bangs, no tasers, even their gas masks can be rendered obsolete.
Meth labs are scary shit in their own right... it makes me nervous when I hear about those warrants.