Tricopter drone frames have only 3 motors, which make them ideal platforms to use as they are usually lighter and cheaper to build as you only need 3 motors/ESC. However because of that tricopters can't lift as much as multirotor with more motors. Another unique feature of tricopters is that the rear motor tilts via a servo to control yaw rotation. If you like the tricopter configuration but want the be able to lift more then you can also consider the Y6 configuration which mounts motors in a coaxial configuration, so you have two motors on each arm. The added benefit of the Y6 configuration in addition to the large lift capacity is thrust redundancy, if one motor fails you still have another one on the same axis to keep your multirotor drone stable, for more infromation see our garticle on airborne multirotor motor failure.