An art film (also known as art movie, specialty film, art house film, or in the collective sense as art cinema) is the result of filmmaking which is typically a serious, independent film aimed at a niche market rather than a mass market audience. An art film is "intended to be a serious artistic work, often experimental and not designed for mass appeal";they are "made primarily for aesthetic reasons rather than commercial profit" and they contain "unconventional or highly symbolic content." Furthermore, a certain degree of experience and knowledge are required to understand or appreciate such films; one mid-1990s art film was called "largely a cerebral experience" which you enjoy "because of what you know about film". This contrasts sharply with mainstream "blockbuster" films, which are geared more towards escapism and pure entertainment.

While "experimental" covers a wide range of practice, an experimental film is often characterized by the absence of linear narrative, the use of various abstracting techniques—out-of-focus, painting or scratching on film, rapid editing—the use of asynchronous (non-diegetic) sound or even the absence of any sound track. The goal is often to place the viewer in a more active and more thoughtful relationship to the film. Many of its more typical features—such as a non-narrative, impressionistic, or poetic approaches to the film's construction—define what is generally understood to be "experimental".

Source 1: http://en.wikipedia.org/wiki/Art_film

Source 2: http://en.wikipedia.org/wiki/Experimental_film