A:Answer Hello, thank you for your question and congratulations on your new Advantium purchase! There are several differences between 120v and 240v. For example, 240v is 4x-8x faster than conventional cooking, can have multiple heat functions on at once: microwave, fan, upper heat, lower heat, interior lights, etc., and no preheat necessary, except with convection cooking. 120v is 2x-4x faster than conventional cooking, heat functions cycle one at a time: microwave, fan, upper heat, lower heat, lights, etc., and has a separate light for the interior light; light stays on. While 240v offers many advantages, it is not approved for under-counter installation whereas 120v is approved for under-counter installation. We hope this helps! Please feel free to reach out with any further questions or concerns. -Chris@GEA