I'm not sure I agree with those ways of thinking about introvert and extrovert. It's not simply if whether you like hanging out with others or prefer being alone. You don't flip from being extrovert to introvert just because you have a time in your life where you prefer to be alone. Extroverts don't become introverts while grieving the death of a loved one.

It has to do with whether hanging out with others drains or fill you with energy, mentally.

I love hanging out with people, it fills me with joy, and I'm great at talking with people, I'm good at cracking jokes that causes a group to laugh, I can hold speeches just fine, or perform in front of a group. But once I'm done, I'm exhausted, it's like holding my breath, I need to come up for air and be alone, even if I enjoy being with other people.