A benefactor is someone who donates resources, either time or money, to another person or an organization. The word comes from the Latin bene facere which means do good.
Side note: a malefactor is simply a criminal, someone who does something wrong. It is not necessarily someone who gives aid to a criminal.
A patron can be someone who gives financial resources to an organization or individual. In the past this was particularly to artists who had a patron who paid the artist’s living expenses so the artist could just think about the art.
Today the term patron can also mean someone who buys something from a store.
In general, the two terms can be synonyms; however, most of the time benefactor is someone that gives to help someone in need while patron gives to something that is seen as unnecessary, like art or music. But in truth, the distinction is arbitrary unless one is speaking of an organization that has defined the terms as part of charitable donation categories.
A mystery benefactor has donated £20,000 to help save a Moray toddler’s life. [Aberdeen Press and Journal]
Now, possibly before you even realize anything has happened, this malefactor can visit likely websites and try logging in using the stolen account. [PC Magazine]
Nigel Pearson has campaigned against racism and is a patron of the charity Show Racism the Red Card. [The Guardian]
Now Sirian has agreed to sell the bar to a regular patron, who says he wants to preserve its unique character even as the neighborhood becomes gentrified around it. [Minnesota Public Radio News]