Is there really a difference between OLD religion and mythology?

The different is that in religions, some people said: I Saw This.. I Really Saw That! In Mythology no, officially are all invented stories.

Bye and best regards

A myth, from the Greek mythos, is a divine story. It is a story about some deity or divine being that explains some part of a tradition, an event, or a culture. Religion is a system of beliefs and practices observed by a person. Mythology is a crucial part to every religion (including modern religions) and the classification of something as a myth is not a statement about whether it is true or false, but rather a statement about whether it pertains to the divine or not. The Bible is a book of Christian mythology for instance. The difference is that in ancient cultures, the mythology was not believed to be strictly literal, and more allegorical and loosely based on universal truths rather than facts (in all fairness, the Bible too was written in this way...literalism is a modern invention...as well as fundamentalism). So, it's not so much a fine line as it is a difference in what aspects are described by each word. The myths are the stories about the gods, the heroes, and whatever else constitutes a divine being. The religion is the system of beliefs and practices, the rituals, the feast days, etc. The religion includes the myths, but the myths are not the whole of the religion.

Venus and Hermes Bless

Mythology is a collection of myths (stories). Religion is a practiced set of beliefs, often formed around those stories. Almost every religion has its own mythology; however, some people dislike the term being used regarding their own religion, as they perceive it to have negative connotations.

I think they're very closely related but obviously separate things.

Mythology is generally an aspect of religion though.

Mythology is simply a religion that is not widely practiced

Well you think wrong...even in Ancient Greece, Socrates was put to death for showing BY REASON that some of the mythology was blasphemous. And Plato was famous for attacking the wrong views of Homer and Hesiod. From Aristotle we get the first set proofs of the existence of God.

No, not only is there a difference but mythology was known to be blasphemy from the start, the attempt to justify sexual perversion and violence by projecting it on to the divine realm.