A summary trial is a type of trial. In our two-tier system of justice we have courts martial and we have summary trials. You can think of summary trials as occurring at a unit level in front of the commanding officer, for example. The court martial, of course, is like a criminal court.
When I say “pretrial”, it's a question of time. It's the events that happened before the court martial was convened, for instance, as opposed to post-trial, when there might be an appeal.