What are term describes a type of variety that adds interest to a design by using two or more elements that are very different?

The term that describes this type of variety is "contrast." Contrast involves incorporating elements that are significantly different in characteristics such as color, shape, size, or texture to create visual interest and dynamic appeal within a design. By juxtaposing these differing elements, designers can highlight key features and draw attention to specific areas, enhancing the overall composition.