A feature film is a film or movie that is the main event when you go to the movie theater. A feature film is different from short films that are sometimes played before the start of the feature film in the cinema.
A commercial film is a movie created with the intent of making money. Most movies you see in the movie theater are both feature films and commercial films. It is possible for a film to be a feature film but not a commercial film. Alternatively, it is possible for a film to be a commercial film but not a feature film.