We know the hair color terminology you’ve heard at the salon often sounds like another language. So we’re here to translate. Up next: Breaking down semi-vs-demi-permanent hair color. The biggest difference between semi and demi is permanency. Though both are temporary, demi lasts 24 to 28 shampoos, and semi lasts 3 to 6. We’ll go through exactly what they are, and why you would use them, with tips from our colorists to help you get the best results. Read on to find out more of the differences between these two popular picks.