Yea I don't think that is it. I mean power man and iron fist only have four books. Black Widow two maybe one more. Tomb has 5 books. The only thing I can think of is possibly the content is a little more mature, so when they labeled them they made them complete collections to separate them from the Epic line. But later on when Conan comes out they said Epic is a better brand so lets just make it Epic even if its more mature. Just a guess.