From Wikipedia:
"Although it tastes and smells much like Campari, Aperol has an alcohol content of 11%—less than half that of Campari. Aperol and Campari have the same sugar content,[3] and Aperol is less bitter in taste. Campari is also much darker in color"
https://en.wikipedia.org/wiki/Aperol
From The Hungry Bites:
"Aperol is an Italian aperitif with scents of orange and rhubarb as the dominant flavors and other herb infusions that complete its character. It has a bright distinctive orange color, and the taste starts sweet but ends with a pleasant bitterness.
. . . and
"IS APEROL DIFFERENT THAN CAMPARI?
Though the two drinks have some similarities (they’re both infusions of fruit and herbs in a bitter liqueur) they’re not the same because Campari has a heavier, rich wood-rhubarb-floral flavor profile while Aperol is lighter with mandarin and orange peel, higher sugar content and approximately half the alcohol".
https://www.thehungrybites.com/3-aperol-spritz-recipes-and-the-secret-for-extra-flavor