Not if they both provide 4.2000000 volts they will be the same !!!
Another passion I have is Airsoft, and they are the same with their bloody batteries, while a more powerful one does give better rof they also claim a better battery gives more power, range and accuracy which is a load of crap.
Another passion I have is cars and when speaking to people from the us all they talk about is bigger engines too, I drive a 2012 BMW 2.0 Td which is 188bhp 0-62mph in 7 seconds but yet their 7.0 200bhp 0-60 9.2 sec motors are faster ?!!??
Boys and their toys eh
not really the same just because two devices can out out 4.2 on a fresh battery does not mean they are the same two examples come to mind instantly:
one: a device with regulated output will keep the 4.2 volts even when the battery is well below 4.2 volts were as a unregulated device will drop volts as you are using the device and you will get weaker and weaker hits as you are using it and the battery drains.
two: different devices will have different amps it can output and two MODs outputting 4.2 volts but are capable of different amps will hit differently the one that can handle higher amps will be able to heat the coil faster and maintain the current, were as the lower amp device might take longer to heat up and not be able to maintain the power throughout the hit giving a much weaker hit.