Well shit, my bad!The first link does not discuss any particular foam guns.
The second link doesn't even talk about foam guns. It is referencing foam cannons, which are used with a power washer.
After further research, a lot of them are pretty similar. It basically comes down to a few things:
The Gilmour has two guns, the Foamaster and Foamaster II. The first has brass fittings and a brass pin that is adjusted to raise/reduce the amount of soap used. The second uses a plastic wheel that is easier to adjust.
There are several companies which basically rebrand these same foam guns. At least one offers it cheaper than the regular Gilmour, but most are actually more expensive.
There are a couple which offer larger tanks right from the get-go, suitable mostly for larger vehicles.
Lastly, the Adams one appears to be quite different, with better construction and performance, but at over twice the cost, not sure if worth it.
I ended up with a regular Gilmour on its way (Foamaster II). We'll see how it goes.
Yes that's the new one. Looks really nice.