Are the people in an age cohort different people in each year or in certain years?

That's a really stupid question, but somehow I'm not so sure. If I ask 20- to 30-year-olds something in 2000 and then ask 20- to 30-year-olds again in 2022, then they're different people, right?
That's why there is a difference between birth and age cohorts, right?