Blue, Indigo, and Violet are all blue. There are five colors in the rainbow, based on how much each peak activates the red, green, and blue cones. The sixth combination of cones, "red+blue", can't be triggered by a single pure color because any pure color would also activate the green cones, so they gave the darker parts of the blue spectrum "purplish" names. They don't look like the color you see when blue and red cones are stimulated together without green ones.
The exact divisions between these pseudo-colors depend on how much damage your eyes take over your lifetime by exposure to solar ultraviolet (utrablue?). Which is a factor of where you live, what your lifestyle is, and whether you pay attention to the eye-doctor about wearing sunglasses.