A festival or gala is an event ordinarily staged by a local community, which centers on and celebrates some unique aspect of that community and the Festival.
Among many religions, a feast is a set of celebrations in honour of God or gods. A feast and a festival are historically interchangeable. However, the term “feast” has also entered common secular parlance as a synonym for any large or elaborate meal. When used as in the meaning of a festival, most often refers to a religious festival rather than a film or art festival.
In the Christian liturgical calendar there are two principal feasts, properly known as the Feast of the Nativity of our Lord (Christmas) and the Feast of the Resurrection, (Easter). In the Catholic, Eastern Orthodox, and Anglican liturgical calendars there are a great number of lesser feasts throughout the year commemorating saints, sacred events, doctrines, etc.
source : wikipedia.org