N2O -- nitrous oxide, what most people call laughing gas -- turns up in a kitchen or behind a bar in one of two shapes. Same gas. Very different day to day.
A cream charger is a sealed unit: 666 g, 2 kg or 4.33 kg. It goes on compatible dispensing equipment, gets used, gets swapped out. Easy to store, easy to keep a spare of, nothing to think about.
A professional tank at 5 kg or 10 kg is a cylinder. Much more inside, needs a compatible regulator, needs somewhere proper to stand. What you get back is a service that does not stop while someone changes a unit.
It comes down to volume. A pastry bench working to order will not miss a tank. A hotel kitchen running foams across three services will feel the difference immediately. Anywhere in between, ask yourself how often the change gets in the way.
The rules do not change between them. Both are supplied for lawful culinary and food-service use, with equipment the current manufacturer instructions list as compatible, inside the regulations that apply. Check before use, never run damaged or wrongly connected kit, and follow the manufacturer on handling, ventilation, storage and disposal.
Not sure? Tell us what regulator or siphon you have and we will check it against the listing before anything is arranged.