These two words can be tricky—and are easily confused.
Adverse means opposing something or causing harm, and usually has to with an object or action. On the other hand, averse implies being reluctant to do something and usually involves a person.
Here are a few examples:
He had an aversion to the monthly strategy meetings—they’re just too long.
A year ago, a poorly executed social media campaign caused some adverse publicity for the company. The executives have been averse to all social media ever since.