BigTb17

Resistance makes a difference and is a helpful rating. Resistance basically creates heat when you pass current through it. The difference may be small when you look at it as only a .00045 Ohm difference. But if you consider that the MMM has less than half the resistance of the Traxxas ESC the difference becomes much more interesting. With equal current flowing through each ESC, the VXL3S would create over twice the heat of the MMM from internal resistance. There are more factors at play and it's not quite that cut and dry simple, but that's the basic principle.

Resistance isn't the only thing to consider. Heat dissipation ability is important. There are other components that create heat as well, primarily the BEC. In many ESCs the BEC is just a linear regulator which is inefficient and creates a lot of heat, particularly at higher voltages. Some ESCs (the MMM is one of them) have a switching BEC, which is more efficient, particularly at higher voltages, and they create less heat. There are many factors.

Ratings also vary by manufacturer and application. In many cases "continuous" simply means an amount of time greater than a split second burst. 200 amps is a seriously huge amount of current and is very likely not a "true" rating. Meaning, I would put money on the table that the VXL3S would melt in a relatively short time if it had a full 200 amps flowing through it "continuously".