Lets see.. Drug Cartel = No cut taken out from the drugs you process when owned. Also money accumulates over server session 3.1k per 5 minutes, if you own Drug cartel you can take the money out and sell it at rebel. Money is added to drug cartel when people process drugs.
Arms Dealer = Reduced ( 20% I believe ) prices when purchasing weapon shop items when owned. Also money accumulates over server session 3.1k per 5 minutes, if you own Arms Dealer you can take the money out and sell it at rebel. Allows you to craft 50. cal. offroad, ifiri and mk200 when owned. You can also buy mk200 when owned. Money is also added when people purchase weapons at the rebel outpost I believe.
Wong Triad = Money accumulates over server session 3.1k per 5 minutes, if you own Wong Triad you can take the money out and sell it at rebel.
Oil Cartel = You attain more rubber when processing oil when owned. Rubber is added if people are processing oil that you can get from OIl Cartel.
Rodopoli turf = Increased drug gathering speed, does not effect ephedra. You can see how many people total are in the turf when owned.
Panagia turf = Discount when crafting ( 25% I believe ) if your gang owns turf. You can see how many people total are in the turf when owned.
Zaros turf = Increased pay amount when chopping vehicles and when robbing gas stations when owned. You can see how many people total are in the turf when owned.
If you own 2/3 of the turfs which is the max you can own, you then get a discount when buying weapon shop items that stacks with the Arms Dealer discount when purchasing.