That's true . . . . in a sense
Given equal loads, a 240 volt circuit uses only half the current of the same thing done with 120 volts (120 volts at 20 amps is 2400 watts and so is 240 volts at 10 amps) so theoretically, the resistance losses in the 240 volt circuit are less - If you use identical wire sizes in both cases, they are definitely less, though you'd have a hard time comparing the losses as they are very small
Usually though, wire is sized by the current flowing in the circuit. Here in the USA, we use 12 gauge wire in most electrical outlets because they are usually rated at 20 amps, and 12 is the correct size for 20 amp circuits. In Europe where everything is 240 volts, wire sizes are smaller because the same load requires only half the current - A 2400 watt load is only 10 amps, so no need for 12 gauge wires. The savings in wiring everything with smaller gauge wiring is significant in this day and age - 240 is definitely the way to go. A 100 foot 20 amp extension cord is now around $50 . . . . it would be about half that if it was used for a 240 volt system because the wire size would be smaller and it would contain about half as much copper. European outlets are far superior to ours as well - There is no way you can shock yourself plugging in a cord there . . . . the pins on the plugs cannot be touched once they are 'live' whereas ours can be
It's unfortunate that we never switched over to a complete 240 volt system like they use in most other parts of the world 50 or 60 years ago when it was proven to be so advantageous - We did make that switch in automotive electrics in the 1950's when 6 volt systems were proven to be inferior . . . . why we didn't carry that over to all AC circuits is a good question - Maybe because copper was so inexpensive back then (it was once so cheap we used it to make pennies) it was decided that we should just continue to go ahead with our 120 system using larger wiring?
Don