Marketing is not sales. It is all the activities that result in building awareness and desire for a product. While selling is the actual act of giving someone something they need, in return for a payment. It is a distinction that you need to understand. Let me explain.
Marketing and Sales of Films
For commercially released movies, the posters, billboards, and Ads (in newspapers, radio, TV, social media) and critical reviews all help increase awareness of the film. These let us know that a certain movie is releasing on a certain date. It usually lasts till the movie leaves the theatres.
For art house films, marketing is based on critical acclaim, the festivals its been to, the awards it received and so on. Building on top of that you could get a theatrical release and repeat the marketing process of a commercial movie.
But marketing does not bring you back money. That is what selling is. Sales is what happens when a person pays to watch the film. It can be in a theatre, on a streaming service, on DVD, on TV and so on. If the film is good, this can happen forever.
Just for a moment, think of bread. Did you think of it in slices? But when sliced bread was invented, no one wanted it. 15 years later ‘Wonder’ figured out how to market it. That changed bread’s identity forever and we have the sliced bread that we so regularly use.
Without good marketing, i.e raised awareness and desire for something, any good product is bound to fail.
How many times have you watched a film over and over, because you liked it? You might sit and watch it again if it was airing tomorrow on your TV. A good film, which is marketed well, can be making sales for as long as it exists. Once your film has hit the theatres, do not think its journey is over. There are so many films that flopped at the box office, but turned into cult classics over the years. If your film is good, it could be making money even 50 years later.
Summing up, marketing is the building up of awareness and desire for your film; by winning awards at festivals, running ads, word of mouth, and so on. While sales is that which happens every time you earn money from the film.
If you are going to distribute your film, it is important that you understand the difference between marketing and selling. Moreover, in the eyes of a seasoned producer, these experiences and knowledge will increase your value as a director.