the first one is the typical stereo type of a dragon, but in legends and myths its depicted as wise and cunning, and they usually talk as well. story books often say that dragons like this are like some kind of mischevios trickster that either plays with your head for a bit and then kills you, or helps you on your way. this is implied in skyrim as the good dragon that helps you has front and back legs and wings, and this one talks to you, whereas the wyverns ("proper" name for back legs and wings instead of arms) all try to kill you without remorse and only roar and hiss at you, never saying a word and lusting for blood. in books the wyverns tend to try and kill you at all costs and are usually evil, but there are a some good ones dotted about in certain stories, btw good dragons tend to be happier colours that one thats out to kill you. also even though wyverns are crazy and trying to eat you, they tend to be described as really skinny and lanky, with massive wings and smaller, thinner bodies. and the 4 legged 2 winged ones are usually bigger, more muscly and have wings that look they could only just lift them off the ground...just. also both kinds of dragon tend to small webbed wits between their feet.
hope i helped slightly and not just bored you to death while i project my obsession with dragons to a webpage.
