@gilles
color of the olives has significant impact on the flavor and health profile of the oil that’s pressed from them
greener olives are unripe; they contain more polyphenols (antioxidants responsible for most of the health benefits), taste more bitter, pungy and peppery
oil yield from greener olives is smaller but it's healthier and has a more interesting taste profile
purple to black olives are riper and fattier, its oil therefore tastes nuttier, softer and sweeter; also because much lower in polyphenols