A patron, usually someone’s parents, works a separate job (often unrelated to filmmaking) and pays the living expenses of the filmmaker.
This can also be true of non-profit organizations held together through public funding.
In this case, the ability to make movies is generally unrestricted.
The filmmaker is limited only by the money they raise & the pleasure of the patron.
Here the financial success of the movie is not as important as the quality of the expression.
This is because the living conditions of the filmmaker are not dependent on the movie itself.
Because funding comes in advance, and is based on the quality of the relationship between the artist and the patron, artworks generated are often avant-garde.
Under the patronage model, the artist defines success in other ways such as popularity, social impact, or critical acclaim.