Western Dragons

a typical Western Dragon in modern fantasy, from Dungeons & Dragons

Western Dragons are Dragons with four legs and a pair of wings, i.e. six limbs. This makes them different from any other kind of vertebrate. How this is possible is discussed in the article about Flight.

The name Western Dragon comes from the Dragonology-series of books, where it labelled all kinds of European dragons. In Japan, all dragons from western myths (Western Dragons, Wyverns) are called doragon (jap. ドラゴン), to separate them from eastern dragons, called ryū (jap. 竜).

Traditional depiction of a dragon by Johann Jakob Scheuchzer

In older Illustrations, for example from the Middle Ages, most dragons resembled winged lizards with talons and serpentine tails, but most times the wings were far to small to actually fly with them. Later, these designs influenced early reconstructions of dinosaurs.

When it became known that dinosaurs weren't sluggish, lizardlike animals but stood upright like modern birds and mammals, this influenced fantasy-dragons, so that they were depicted as standing upright, too. Today, most western dragons in fantasy look somewhat dinosaur-like.

Dragons of this kind are mostly known from European myths, hence the name, and today they are the standard dragons of classical fantasy works (besides the Wyvern). Especially if there is only one kind of dragon in a work of fiction, it will rarely be anything than a western dragon or wyvern.

Puff, a Standard Western Dragon

On the other hand, if there's more than one kind of dragon, western dragons (often called True Dragons) are the most powerful kind of dragons, while other kinds of dragons like wyverns or lindworms are denoted as Lesser Dragons or Draconic Creatures. Examples are Dungeons & Dragons, where it's distinguished between True Dragons and Draconic Creatures, or Monster Hunter, where Elder Dragons are much more powerful than the various kinds of wyverns (Flying Wyvern, Bird Wyvern, Brute Wyvern...).