The Definite Article with the Names of Festivals

I have noticed that the definite article the is always dropped before religious festivals, such as Easter, Passover, Christmas, Eid-al-Fitr, etc. However, it is always used before film festivals , such as the Cannes Film Festival, the Chicago International Film Festival, the Canberra International Film Festival, etc. The problem is with the names of cultural festivals around the world. Some are used with the definite article, others are not. Burning Man Festival and the Boston Seafood Festival are just two examples.
I am wondering why the definite article is used with some cultural festivals and dropped with others. And is there a reasonable explanation for this or does it depend on the context ?