Gas Bottles

AFAIK no difference. Both have the same connection and use the same gas. For instance you can use a "swap & go" bottle on either.

There are 4 grades of LPG bottles, Grade 1 is from memory Galvanized and is for marine applications , Grade 2 is suitable for carrying on the A frame of your caravan, Grades 3 and 4 are a lighter grade and are for patio use.
If you check the collar of a bottle you will find a number inside circle, this is the one you look for when you are swapping your bottle at a "Swap and Go", that as well as the date.

rr VKE237 sel 6678

I would think its more important to look at the retest date and get one with a long validity. If the cylinder gets corroded , just swap it for another one.

After all the differences are all about corrosion resistance, and you do not "have to" use any one of them.
Regards Philip A

LPG cylinders come in different sizes for a similar capacity too.

If you check the ELGAS site, their 9kg Swap'n'Go cylinders are listed with a diameter range between 309mm-335mm are a height range between 450mm-525mm.

That is a large variation when you are looking for a replacement cyclinder for your camper or caravan where it is retained by a circular clamp for instance.
The height may be less significant although the higher size range may cause problems for BBQs and Heaters.

I do not use Swap'n'Go cylinders and purchase mine from the same retailer which have an option for one's in both 9kg and 4kg with a built-in gauge operated by an internal float. These are consistant in both height and diameter measurements.

Why the variation in size, even from the same manufacturer, I have no idea.

Here's another type of gas bottle which has been available in the USA for several years.

Lite weight gas bottles

Er I was not advocating Swap and Go. I usually use Ray's Outdoors for refill as I find them cheaper than most and I get a discount.

BUt I must admit I did swap my almost out of date 4Kg for a Swap and Go one with a 08 inspection stamp. LOL. It is much cheaper than buying a new bottle.
Regards Philip A

Check out Gas bottle standards

From above regulations

1 Hot Dip Galvanizing

2 Abrasive blasted + inorganic zinc rich coating + organic zinc rich coating.

3 Sprayed Zinc Coating

4 Red oxide or polyester powder coat.

Stainless steel would probably be the best for caravan usage, but they are likely to be quite expensive. So, when exchanging gas bottles, the number 1 in the circle should be preferred. The number 2 bottles should be the minimal treatment for caravan usage. The number 3 and the powder coated type with number 4 in the circle should be restricted to home use.

Most of the swap bottles I have seen are for home use only so I always get mine filled.

Pedro