I've looked up these two phrases on the Internet, and I've found out that most websites and sources usually contain the phrase "people of different ages" or "people of different age groups".
I rarely encountered the collocation "people of different age" as it stands with the "age" in the singular without additional words after "age" in this collocation.
Am I mistaken, thinking that "people of different age" is not typical of native speakers?
Promoting collaboration between people of different age groups is a primary way to conquer ageist attitudes.
They found that younger participants were more likely than older people to endorse the stereotypes. People of different ages are equally as likely to endorse descriptive stereotypes. .