There are various other aerial vehicles that can be used. Humans have successfully made helicopters and airplanes for transportation, surveillance, and even war. Can Quadcopters be used for such causes? Are there any other benefits? Obviously, each vehicle has its own advantages and disadvantages.
Quadcopters and almost every other multicopter craft uses its motors and propellers to produce the necessary thrust needed for the lift, whereas airplanes use motors to produce speed. The lift is achieved by the aerodynamic model of the plane and its wings. So the asset of a quadcopter is the stability that it offers; thus providing a great opportunity to capture photos and videos. On the other hand, airplanes are much faster because of their aerodynamic design and as a result they need less power than helicopters and quadcopters, where all the lift is produced by the motors.
The main difference between a quadcopter and a helicopter is the number of blades used for the lift. A helicopter's mechanism is extremely difficult to build and work properly, whereas quadcopters are pretty simple. A helicopter produces all the lift needed, which is equal to its weight, with only one blade. As a result the total mechanism is quite complex. On the other hand, the stability in a quadcopter comes from four motors with their blades and it's quite simple to understand and create. Thus, the mechanism is quite simple. When a blade is spinning, there are two things that happen. First of all, there is thrust, which lifts the craft. Secondly, every motor creates torque, which is why a craft with only one blade would spin around itself. In a helicopter, a rear blade is used to prevent the craft from spinning around itself. On the other hand, in a quadcopter, all the lift is produced by the sum of each motor's lift, which must be equal to the quadcopter's weight. But, instead of a rear motor to prevent the craft from spinning around, each motor eliminates the torque that the opposite motor produces. As a result, the quadcopter hovers steady without spinning around itself.