The secondary colors- orange, green and purple are th product of mixing two primary colors together. They are positioned midway between the primary colors from which they are mixed. These form an equilateral triangle opposite in position to the primary triangle:

Secondary colors when used together have lessened color contrast than primary colors. For example green and violet are secondary colors which both contains the primary color blue . the influence of the color blue creates a commonality between them. Softer color contrast is the result.