Why the Australian Tomahawk steak is larger then US?

Question

If you do a search for Tomahawk steak on Google Image, you will see two very different Tomahawk steak, the US ones, some simply referred it to Rib Eye Bone-In French Cut, are much smaller, with smaller bones at the tail and much more elegant looking. While the proper Australian Tomahawk is so much larger in pic, and weight in 1.8Kg+.

What are the different between these two parts? Are they even made with the same cuts?

Answer 1

Here from this native seller of the Australian Tomahawk steak we see of its size in terms of weight an

Average weight 24 to 96 oz.

This particular seller handles (sells) steaks only between 64 and 80 oz. But its product description is clear on the fact that this amounts to cherry-picking (see photo?).

Since 24 to 96 ounces represents such a wide range of sizes compared to the correlative 64 ounce example you cite, what we're looking at here, in the way of an explanation, is that some cattle are simply larger than others. This would necessarily mean that, sure, you can find just as large (or small) a cut in the U.S.

Answer 2

They are the same cut.

Quoted from Meat 102: Cuts, Anatomy & Preparation (emphasis mine):

Some restaurants will call the ribeye a “tomahawk steak” if the entire rib bone is left on and french cut by the butcher, since it then looks like a small hatchet. It is common for butchers to cut the bone down a bit, however, for packaging purposes ... Sizes and portions range from anywhere between 14oz to 36oz, most often hovering around the 20oz mark in restaurants.

36 oz is about 1 kg, or half as large as the "Australian Tomahawk" -- which can be attributed to having the full rib bone, as well as probably a thicker cut (and a generous pinch of marketing-speak and publicity).

The Tomahawk is one of largest steaks in Australia, weighing in at 1.3kg – 3.6kg (1.8kg average). Each Tomahawk is a rib-eye, or scotch fillet on the bone...

(see also StockJournal article)

EDIT: It's also called a cowboy steak or cowboy chop. So, the uncut rib bone seems to be the primary difference between "Australian" and "US" tomahawk steak.