The difference between "effect" and "affect" is that "effect" refers to something that is produced by a cause while "affect" is the act of producing an effect or change. "Effect" is a noun, and "affect" is a verb.
"Effect" is defined as a result or consequence produced by a specific cause, and "affect" is the act of causing something to happen. One example of "effect" used in a sentence is, "The flooded streets were an effect of the rain that poured down all week long." An example of "affect" used in a sentence is, "The lecturer attempted to affect the feelings of the audience with her radical speech."