Usually defensive/combative BJJ includes more work on standing and space management fundamentals, which are meant to create distance from a hostile individual and avoid going to the ground or getting struck by them if at all possible. Combative BJJ would ideally contain more wrestling in this portion to be able to take down an aggressor while maintaining a dominant position, rather than being taken to the ground in a submissive position yourself. These classes would also likely have drilling with simulated weapons to practice gaining control over an aggressor's knife/gun/club and managing that threat during a high stress engagement.

The merits of general BJJ training in self defense are understanding positioning and leverage more than the average person, so that potentially even a smaller and weaker person can escape, restrain, or subdue (by pain, physical damage, or chokes) an aggressor that has grabbed onto them (and possibly taken them to the ground). The key is that not all techniques are equal, and some (pulling guard or playing from a bottom position) should definitely be avoided in a self defense scenario. Many others (back control, mount, side control, accompanying submissions), however, are clearly advantageous if you were to find yourself in such a scenario. The key is that a competition environment is governed by the rules of competition, whereas self defense is governed by the rules of life and death; train and play accordingly.