If you look at the icons for a prolonged period directly then yes, it's easy to differentiate between the two. However, in battle you're going to constantly be checking back on your status effects as well as other parts of your UI and not to mention the actual battle. As a result, it's common that players including myself have to rely on our peripheral vision to determine our next action within a split second. For example, on DRG when I see a white and purple icon lowering in single digit values, this indicates that I need to execute a disembowel + chaos combo soon for my next rotation. I don't look exactly for the pink petals or the shape of the spiked man in each icon, it's faster for me to differentiate based on color. The ninja icons share blue and purple color palettes which are difficult to differentiate. Mutilate is much easier since it's the only ninja icon that is green.