Orcs on both sides

[Inziladun]

Originally Posted by Alfirin

That is that Melkor found the dragon nature so well suited to his needs (quite possible, given how long it took the armies of the west to find a way of dealing with them) he used the dragon "template" more than once, to various creatures (possibly eagles for the flyers, lizards for the walkers and snakes for the crawlers), and so created the three main draconian races.

My opinion is that the various breeds of Orcs might have been similarly "made" over millennia using various races of Arda, even though the Elves would seem to be the most likely originals. So I can go along with the idea that dragons might have some differences in makeup, though they plainly share some common traits, most notably in behavior. Both Smaug (flyer) and Glaurung (tail-dragger) had a liking for finding a treasure hoard and sitting on it, and that possessiveness of gold seems to have been a well-known dragon trademark.