Discussion: What is the difference ?

What is the difference between “epidemic “ and “pandemic “?

In early 2020, just after the Covid-19 pandemic broke out, I watched YouTube to get some information about the situation. I found the word “epidemic “ was used very often. But gradually, the word “pandemic “ can be seen in most mass media instead. It seems “pandemic “ is more serious and fatal than “epidemic “ when talking about the severity. Am I right?