PANTONE colors are specific mixes of pigments, not RGB or CMYK values. A PANTONE color includes elements like texture and lustre in its definition that cannot be captured in primary-color systems like RGB or CMYK. Certain trademark shades, like Tiffany blue, are captured as PANTONE colors as well. PANTONE is the standard for print graphic design because a designer will always know exactly how a PANTONE color will look on paper whereas significant calibration is necessary to get a consistent appearance from RGB or CMYK colors.
Yes indeed, the lustre makes a huge difference with some colours - sometimes even affecting the perceived hue, not just the vibrance - Pantone 136C vs 136U for example. Same ink, different paper.
