Some films are about myths, some films are mythic, and some films are both. Both Cecil B. DeMille versions of "Ten Commandments" are both about myths and mythic on their own. The moral content of the film is coupled with their content: which is drawn directly from Biblical myths.

The animated Dreamworks production "The Prince of Egypt" is about the myth of Moses just like the "Ten Commandments" movies. "The Prince of Egypt" does deliver a moral message, although one that is milder in tone than either of the "Ten Commandments" movies, Kie-lowski's "The Decalogue" or David Hugh Jones' "The Confession." Furthermore, animation enhances the mythic components of "The Prince of Egypt." Because the film is animated, viewers can suspend disbelief and surrender to the power of myth.

Krzysztof Kie-lowski's "The Decalogue" attains mythic dimensions as a film because of its powerful moral messages. The moral meaning of "The Decalogue"...

Unlike the Cecil B. DeMille movies, Kie-lowski does not structure his film around the Moses myth at all. Instead, he depicts modern people and events. The characters themselves are not mythic, but because the film is structured and produced based on the Bible, "The Decalogue" deserves to be called mythic.
On the other hand, "The Confession" alludes to the Ten Commandments without being about the myth of Moses or a mythic film. Many movies send the message that killing, lying, and cheating are moral transgressions and do not need to refer explicitly to the Bible to do so. "The Confession" could easily be a moral movie without any religious references, and therefore it is neither mythic or about a myth.