How can you tell the difference between someone born in the early ’80s (1983–1986) and a core Millennial (1987–1992)?

I notice that people born in the early ’80s had most of their childhood in the ’80s, so they tend to relate more to that era. But those born in the late ’80s and early ’90s often vibe more with each other. They’re from different birth years, so their experiences can be a bit different. Early ’80s–born Millennials are in their 40s now, and some of them even have kids who are younger Gen Z.