Its a completely different system of oxy production. With your oxy bottle or home oxy generator, you have a steady supply of oxy via the cannula into your nostrils. The portables use a different technology, due to their size, and they push oxy into your nostrils as you inhale which means you get much more oxygen per breath than at home or hospital bed. However, I still haven't come across an expert who could translate how much would I need to ramp up the power in my portable oxy gen to reach 5 ltrs. I usually take the portable on trips (frequent) and use it at nite, and put the output at 2 or rarely 3 out of five. So do whatever you feel good with. Re weight - the batteries and the oxygenerators inside (look like two big batteries) are the heavy parts, but that can't be avoided. I really can't say which one is better but the one you are looking at is a lot cheaper. That doesn't mean that is it necessarily worse, at all. So please do consult your physician on this. All I can tell you with conviction is - buy one, you wont be sorry and you will see its a good investment. Re noise - don't be bashful - weddings are always noisy. GL