Examples may include, winning a championship, a wedding, winning the lottery, or receiving an unexpected A on an exam.
Distress is stress caused by an event in one' s life.
Examples may be failing an exam, divorce, notification of a tax audit by the IRS, etc. In summary, when you see the term eustress in the literature, it is referring to a positive stress. Whereas, distress is referring to a negative stress that can lead to disease.