Are Legendary and Epic the same thing?

I noticed that all Epic creatures are also legendary. Can these terms be used interchangeably? Is Epic and Legendary the same?

No, these terms are not the same. Epic refers to a character's rarity, while legendary is a term related to the game rules that allows you to put no more than 1 legendary character in a party.

While most Epics are legendary and vice versa, there is an exception: Chen Stormtout. This character is Legendary, but is not epic (it is only rare).

Yeah I got confused as well, when I pulled a Chen Stormtout I was sure that I got an Epic