The Taxonomy of Drakes

Drakes, Dragons, Wyverns, Wyrms, Qilin, Leviathan. Hotly debated even among experts, such terms are somehwat ambiguous, or at least they were. An unknown Terr'ainan scholar on a Zhisien, or search for knowledge, attempted to categorize all of these creatures, amassing volumes of notes, research and samples. Currently at Hon-shu of Xian on display, these notes lay forth the most commonly accepted ideas on "Drakes".
Drake is first accepted to be the "order" of living thing, as variation within is too diverse to classfiy them as a family. Drakes are incredibly diverse, and finding any broad similarities is difficult, but generally all are partly scaled, are vertebres, and have more than 2 limbs. Most have tails, claws and horns.
Within Drakes we find the families of:
Dragons
True Wyrms
Lesser Wyrms
Qilin
Winged Wyverns
Clawed Wyverns
Hybrid Wyverns
Leviathans
As has been pointed out by plenty of experts, these families are far from perfect. Leviathans could easily be considered a kind of Legless Wyrm, and the entire idea of the seperation of Wyvern types has been called into question more times then can be counted. However, for the ease of scientific and magical study, these terms are commonly accepted, and are what most normal people abide by. Below is a more in-depth explanation on each of the families.
Dragons are by far the most iconic, and the easiest to seperate. Dragons have 6 limbs - two pairs of legs, and a pair of wings. To be a dragon, these wings must be full limbs, even if they do not grant flight. Beyond that, Dragons are omnivores, but do require meat to obtain necessary nutrients. Dragons also have a higher intelligence than most other drakes as a baseline. Often larger, longer lived and much more powerful than other drakes, Dragons are believed to be the oldest family of Drake, and perhaps even the ancestor of the other families.
True Wyrms are still often referred to as Dragons, more so than any other family. True Wyrms have long, snake-like bodies, and 4 or more legs or other jointed limbs. All true Wyms are capable of flight to some extent, and fly by suffusing a special organ with air, much like a balloon. True Wyrms are usually omnivores as well, but unlike drakes, have a much lower nutrient requirement and do not necessarily require meat. Their intelligence rivals that of Dragons, and as such, are often still referred to as dragons in some places.
Lesser Wyrms are not necessarily lower in power or intelligence than True Wyrms - rather they have similar features to True Wyrms, but lack a particular feature of some sort. Some, like the Cliff Wyrm, do not have the ability to fly, while others, like the Rainbow Serpent, have adapted to no longer have legs at all. Lesser and True Wyrm mostly exist as a scientific seperation - to most, the differense between a Cliff Wyrm and a Cloud Wyrm is surface-level.
Qilin are an interesting case, as they are the most different from the traditional drakes. Some have even put forward that they are an entirely seperate "order", but others insist that their presitige and comparable status to Dragons should group them together. Regardless, Qilin are more similar to horses than lizard in shape of body with hooves and a mane, albeit with a mixture of scales and fur. Qilin have a long history in Terr'aina, and numerous subdivisions and species exist within, with almost as much variation as Drakes as a whole. Most Qilin are omnivores, but generally faovred vegetation due to a naturally peaceful attitude. Qilin's intelligence varies - For instance, despite their size, Dwarf Qilin are considered as intelligent as a young humanoid, while the Tree-Splitter Qilin is no more intelligent than a dog or cat.
Winged Wyverns all share a relatively common body plan - two rear legs, large wings and a long tail for balance and adjustment in flight. Winged Wyverns are often compared unfavorable to Dragons, being seen as less powerful and intelligent. While this is often true, some Wyvern species are on par with all but the most powerful Dragons. Winged Wyverns are also the most common type of Drakes to show social dynamics, and many hunt and live in groups, called Flights. In Aerava, Winged Wyverns are almost as common as birds, especially smaller species. Most Winged Wyverns favor meat, but can eat vegetation or scavenge if the need arises.
Clawed Wyvern is a small misnomer - almost all Wyverns have claws. Instead, Clawed Wvyerns all have four legs (though some have the ability to operate only on two for considerable time, using the others like arms). Clawed Wyverns generally make up for the lack of flight due to being absolute apex predators, and are almost universally carnivores. Beyond that, features vary, but generally they resemble canines, felines or lizards in body shape, albeit with the size, scaley armor and imposing weapons of a drake.
Hybrid Wyverns are essentially somewhere between Winged and Clawed. They possess some measure of flight, or gliding, but still have front limbs that oberate as legs. Generally, this takes the shape of membrane similar to a flying squirrel's, or wing-like proturisions on the back of the front legs. Usually not as physically strong as Clawed Wyverns or mobile as Winged, Hybrid Wyverns still have great success in environments that benefit from a bit of both, such as the thick jungles of lower Aeravaen Sky Isles, the dense, ancient forests of Terr'aina, or even as diving species on coastline cliffs bordering Kaiyocea.
Leviathans are the most debated species of Drake, due to a few factors. Firstly is that Leviathans are universally aquatic, and have a body shape closer to that of snakes or eels. Secondly is the complete and nonsensical variation within them. Despite that, they have the temper, size, and cunning of Dragons, and are considered by many Kaiyoceans to be just as majestic. As stated, Leviathan have a wide variation, but all live towards the lower end of the ocean. Despite this, their size dwarfs many species of Sea Wyrm, and even most Dragons. Information about Sea Leviathans is still far less in number than other Drakes, due to their habitat and lifestyles. It's believed most Sea Leviathans actually are quite passive, getting nutrients from scavenging the ocean floor, ambush tactics, and sea floor vents. However, occasionally Sea Leviathan get too large to support this lifestyle, and wander towards Kaiyocean settlements, which has led to a tradition of hunting these creatures.
There are countless other species that resemble Drakes, but are not considered to be as well. Not to mention that the entire existance of Drakes as a classification is entirely due to one now-unknown scholar. No matter what you may call them, its hard to not find the wide variety and diversity in Drakes awe-inspiring.