Both Post-Inflammatory Hyperpigmentation (PIH) and Post-Inflammatory Erythema (PIE) can occur when an acne spot clears up. But, there is an immense difference between both skin conditions. In PIH, dark or brown spots appear on your face due to excessive production of melanin.
Contrarily, PIE triggers red, pink, or purple marks due to blood vessel damage underneath the skin. PIH affects people having darker skin tone while people with lighter skin tone are more prone to get PIE.