"Patron" is not used often, it's often seen in expressions like "patron of the arts". A patron of the arts is someone who donates money to museums or symphony orchestras, or buys fine art for their collections. There is also a word 'patronage' which has a similar meaning - it is like the act of being a customer. This word is very formal and not used in conversational settings, for the most part. A business owner might make a sign, which says in very formal English: "Thank you for your patronage", which means, thank you for being a customer. "Sponsor" is usually someone who is a contributor or host of an event. You will often hear the words "sponsored by" when listening to the TV or radio, for example: "this show is sponsored by Company A, Company B, and Mr. Thompson". It means these people provided money or other resources so that the event could occur - often done for the advertising value. A patron is usually someone who is visiting an establishment or event, a sponsor is someone (or a company) who is providing support (usually financial) for the establishment or event.

PATRON - The former master of a freed slave. SPONSOR : A promoter, one who pays for broadcast.

maybe these links can help: http://www.wordnik.com/words/patron, http://www.wordnik.com/words/sponsor