Answer:
Well, an extinct species refers to a single species completely dying off whereas a mass extinction happens when a massive number of species all dye off at the same time.
Explanation:
For example, when the asteroid wiped out all the dinosaurs that was a mass extinction, but the gradual disappearance of the African Black Rhino would simply be considered as an extinct species because of the fact that not every kind of Rhino to ever exist was wiped out.
