Here is a good diagram showing the difference between transmitter modes of RC radios. As you can see, Mode 2 is standard in the U.S. and is most common, whereas Mode 1 is used, but not as much, Modes 3 & 4 aren’t very common at all. Really, the only difference between Mode 1 and Mode 2 is the Throttle and Cyclic (forward and back) are switched from left to right. The tail rotor and left / right cyclic remain the same. The difference between Mode 1 and Mode 3 are opposite, tail rotor and left / right cyclic are switched from left to right and the throttle and cyclic (forward and back) remain the same. The same goes for Mode 2 and Mode 4. But, if you really look at this, Mode 3 is the exact opposite of Mode 2 and Mode 4 is the exact opposite of Mode 1.