Yes they are. Hang on, I had a sketchbook in my saddlebags somewhere, hopefully the air on that world we ended up on didn't ruin it.

[Hiccup goes offscreen, and shortly returns with a somewhat haphazardly made book.]

Here we are...

[Hiccup rifles through the book, and opens the page to a large dragon that, unlike Toothless, looks little closer to what Zuko is used to, aside from the fact that it has two legs. Its wings do double duty as its front limbs. There's a wide, brawny looking human with the dragon, and the pair both have expressions of cocky overconfidence.]

That's Hookfang, my friend Snotlout's Nightmare. They're big, strong, have a habit of intentionally setting themselves on fire, and aren't too bright. And by that I mean Hookfang, Nightmares in general, and Snotlout himself.

[The next picture is of a two-headed dragon, which does have the four legs and two wings most people expect. The insane looking twins near it seem to be fighting about something, while the two heads look on exasperatedly]

That's a Hideous Zippleback, specifically Barf and Belch, with Ruffnut and Tuffnut. The right head breathes explosive gas, the left head makes the spark to set the gas off.

I've got plenty more drawings where those came from if you want to see them.