While most of the jobs in the game are issued by Network Bosses, sometimes they are impromptu instead. If the crew wants to attack a local gang of out-of-network criminals, that’s an Assault job. The only difference is the source of the job, not the rules. You use the job resolution rules to find out what happens. A key point here is that the crew decided to attack a local gang. The scale, the amount of acting operative, is what warrants a job versus a contest. If one operative, or even two working together, were to attack the gang, it would just be a normal contest. Three operatives acting together is a gray area and ultimately up to the Director, since the rules do allow multiple sources of assistance in a contest. Once you reach four operatives or more, it’s always a job.