What is the difference between self-confidence and hubris?

Exhibiting hubris is typically a state of excess confidence in the self, so the individual presumes attributes and capabilities that are actually lacking. They are overconfident and so may overreach, take on greater responsibility, or expect a greater degree of freedom and reward than truly merited by their achievements because they simply overvalue their talent and their relative contribution compared to others, believing they are special and are endowed with greater than average abilities. So they are more lacking in discernment and good judgment in not having an accurate perspective of where they stand in terms of their skills and potential value compared to others. This does lead to interpersonal friction and potentially conflict, and is a defect that will hold a person back in life and eventually catch up with them because they will be challenged and it will harm them in the end as much or more than the harm they cause in elbowing others out of the way, for example, or misrepresenting their capabilities to take on a challenge they are not suited for and then when they fail, it may affect the success of a larger enterprise and hurt many others. So it is always regrettable and will have consequences, at a minimum, for the individual themselves from living out of alignment with the true reality of things, and it may well have significant adverse karmic consequences through harm to both the self and others as a consequence of their misjudgment.