Toy helis have 2 motors, one to control the main rotor and one to control the tail rotor. The throttle stick of the transmitter controls power to the main rotor motor and the rudder stick controls power to the tail rotor.
However, the relationship between the two isn’t as accurate as it is on a proper rc helicopter and this is why the directional control of the toy is sometimes a bit vague – if the tail rotor isn’t giving as much thrust as it should, or is giving too much, then the fuselage of the helicopter will want to turn of its own accord and send the model flying off in a direction that you didn’t intend it to.
Contra-rotating (coaxial) rotors:
Contra-rotating, or coaxial, toy rc helicopters have no need for a conventional tail rotor because the main rotors spin in opposite directions to one another, so cancel out the effect of torque and hence the need for a tail rotor.
Turning is achieved by slight variations in speed between the two main rotors, relative to each other, which upsets the torque balance and spins the fuselage round to the desired direction.
Coaxial helicopters can be flown much more accurately than the toy single rotor helicopters, and they generally stay in whichever direction that you put them in, making indoor flight even easier.