The question is complex: epistemologists would say they are two “ways of knowing.” Science is the method of building new knowledge on what is already known, by applying logic, cause-and-effect, physical laws, etc. according to strict rules of the discipline. Art, on the other hand, creates and appreciates according to much more ephemeral “rules” of aesthetics, a subjective reaction to forms, rhythms, connotations, etc. that do not use the same mental functions as science. When we say a mathematical formula is “beautiful,” we usually mean its symmetry, its logic, its “statement” of truth is satisfying. When we say that a sunset is “beautiful,” we are referring to the emotional tranquility, the sense of a universal order it gives us when we see it. Art lets us “know” things by tapping into a universal order using our emotions; science lets us “know” things by showing the relationship between the (until now) unknown and the already known. Your brain does a lot of things – science is one, art is another. On a certain level, they complement each other, and the differentiation is a false one: Is the Eiffel Tower science or art?