Dragonborn is a general category for sapient species hailing from the Ancient Dragons. It is unknown how exactly the 'hailing from' part works - the creation of these species largely predates written sources, meaning that scholars can only try to learn something from orally passed legends. Which, it has to be said, is far from an optimal source. There are many theories, but very few confirmed information. The truth is that the the ancient dragons that survived the fall of the First Empire were being slowly wiped out by a truly terrible curse that rendered them infertile (and the few children that they did have all were eldritch abominations more than dragons). In the desperate bid to fix the damages, the dragons put their minds together and attempted to achieve that through experimentation. Said experimentations - first to lift the curse, and then, when it turned out to be impossible, to create new bodies and transfer dragon minds to them - has resulted in a creation of the dragonborn, lesser dragons, wyverns etc. The ancient dragons tended to kick the functional end-results of their experiments into the wild, resulting in spread of numerous species (both sapient and not) in the wild. Typically centered on the lands now known as the Kingdom of Drakha, which used to house the last bastions of the ancient dragons. Like the Xylmade, there exist no baseline species for the dragonborn, unless one considers the ancient dragons to be it - an unlikely occurence, since it's hard to add the dragons from which the dragonborn were 'born' to the list of dragonborns.
Drakons a diverse warrior-species of partially dragonized people, speculated to be a fusion between humans and dragons (with the human side taking precedence... initially). They are strong and resilient, but the greatest threat is their magic ability and deep attunement with various elements. The drakons are divided into numerous subspecies, based on the element they are attuned to. Said element alters the way they look and grants them powerful natural abilities. High Dragons are an extremely dangerous and deadly creatures capable of shapeshifting between humanoid form (where they slightly resemble drakons) and a fully dragon one. Unfortunately, they seem to have inherited the dragons' desire for conquest and ownership, making them a constant threat to anyone around. The only thing that stops them from being added to the 'kill-on-sight' list of the Grand Empire is the rare few of their kind that decides to satisfy their desires in a more controlled way.