Hi Monique 1
I'll try to answer your questions as best I can.

The main difference between so-called medical grade ozonators are that they are fed with pure oxygen from either a tank with a regulator or from an oxygen concentrator, a machine that extracts mostly pure oxygen from room air. All other water ozonators use room or atmospheric air as a source for the oxygen to be made into ozone. Since room air contains nominally 20% oxygen as well as a number of other gases and impurities, the ozone produced from room air ozonators is less than pure. Medical grade units produce a higher concentration and purity of ozone because they are using 100% oxygen as a feed gas. IMO the medical grade units are the way to go if the need for portability is not an issue and funds are available. A medical grade system will cost considerably more money to get started because not only do you need the machine, but also a pediatric regulator, an oxygen tank and tubing sets. Some local Due Diligence is also required to find a reliable, inexpensive source for oxygen refills. Many people have bought their systems only to find that they cannot either get their tanks filled locally or a prescription is required for the rental of an oxygen tank. There are ways around this.

It is advisable to use a medical system for any internal protocols or for body bagging, ozone saunas and the like. They create far purer and more concentrated ozonated water for enemas, drinking water and oils.

If budget and portability are concerns, then the second best option is an air-fed water ozonator like the Nature Kleen, the ASO 250, the Enaly 400 and countless others. Although less pure, they do a respectable job in creating ozone to ozonate water and oils. Due Diligence is also required when choosing one of these ozonators in terms of features, reliability, truthfulness in specifications, ozone output etc.
There are many inexpensive air-fed water ozonators that will not last their warranty, especially when ozonating oils. Ozonating oils creates more strain on the components.

I assume your voltage in Sweden is 240 volt? you will also have to choose an ozonator capable of running on this voltage. Most North American and Chinese ozonators are 120 volt units. The Nature Kleen and ASO 250 are available in 240 volt. You don't get the bells and whistles with the ASO 250 that you do with the Nature Kleen, but the cell that produces the ozone is identical and specifications are the same. The ASO 250 can also be used with pure oxygen. The Nature Kleen cannot.

The Synergy single cell unit is almost identical to the Mini Med in terms of features and ozone output and the Synergy double cell unit is comparable to the Maxi Med. None of them are true medical grade units for reasons that I can get into later. I've covered this before in posts on Curezone. They are all very respectable units and can be used for almost all ozone protocols.

I'll have to check on shipping costs for you.

There are no dumb questions. Fifteen years ago I was asking the same questions and now I'm happy to share what I've learned.

I hope this helps your understanding of the differences in ozone equipment.

Have an AWESOME day!
cheers,
Paul