Traditional 4 color process uses Cyan, Magenta, Yellow and Black inks to achieve a wide variety of colors and achieve beautiful results. However it does have some limitations, the largest of which is Color Gamut, there are many colors that are outside of its spectrum, so the software and printer is forced to guess at the closest standard color.
8 color extended gamut printers, utilize the same CMYK with the addition of Red, Green, Orange & Blue. These additional colors will increase the smoothness of gradients and overall resolution. But that is not its saving grace, the additional colors dramatically expands the color gamut, allowing more faithful reproduction of colors. Particularly Brand or Pantone colors that are outside the color spectrum for CMYK printers.
8 color ECG prints feature richer, vibrant colors with enhanced midtones, ie shadows, highlights and fine details than traditional 4-color prints . Luxury and Corporate branding may benefit from 8 color ECG printing as it allows more accurate color matching and design color reproduction.
The difference varies file to file, some jobs 8 color ECG will provide marginally brighter colors, smoother gradations and subtle increase of midtones and highlights. While other images the difference will be dramatic, depending on the colors and whether they fall outside the 4 color process color gamut.