In these districts, players can choose to roam about freely, interact with the NPCs or party up with fellow criminals/enforcers (other gamers of the same faction) to duke it out in group-based missions against teams of the other faction.
However, do note that there's several versions of these two districts that you may join (should you choose to do so manually).
"Threat-based" ones which pits you against players of similar "rankings/standings" (skill level) and "Free-for-all" ones, called "Open Conflicts", which just randomly puts players into missions...as and when they become available.
Additionally, these districts also appear to have a maximum population limit of 100 players (50 Criminals and 50 Enforcers).
These districts exist purely to facilitate fast-paced fighting between criminals and enforcers (players).
Though they still involve group-based missions, but as far as I can tell, the fights in these zones are rid of the NPC "distractions" and all their running about.
And what makes it even more fun is that there's only two sides. Your either an Enforcer or your a Criminal. Therefore, so long as there's enough people in the zone, your pretty much assured of a massive shootout.
No guns and grenades are allowed in this zone.Coincidentally, this zone is also where you perform all the customizations for your avatar, cars and clothings.