The Renaissance was the period in Europe between the 14th and 17th centuries when there was a surge of interest in and production of art and literature. "Renaissance art" describes the style of art that came out of this period.
When you see the word Renaissance spelled with a capital R, you can be sure it's referring to the European cultural movement, or the art, literature, and architecture it inspired. The Renaissance began in Italy, largely as an growth of interest in classical art and ideas. The word itself comes from the French phrase renaissance des lettres, used by the 19th century historian Jules Michelet. In Old French renaissance means "rebirth."