Technically, the term applies to those born on or after 1983 which is so amusing because people born from 1983-1988 are quite a generation apart from the 90's born kids.
This is actually quite true in my experience and it speaks to a point regarding the definition of a generation that always bugs me.
From what I understand, the actual time frame of a generation in these studies has some flex to it, in that they tend to point to other studies and try to make the research match with at least average ranges. It also would seem that the whole range of a generation is based on a reproductional generation. Ultimately that is completely arbitrary, and so we need a common anchor point to begin really defining each generation.
That was WW2, we had the great generation and the boomers following. But that's just the thing, without the event, fixing a proper definition on the people born in the late 30s and the late 40s as one generation would be just as appropriate, since time is arbitrary.
So what's not arbitrary then is the event. A large scale impact on society and culture. 70s and 80s kids imo have more in common with each other than 80s and 90's do. Likewise I would group 90s and those born in the new millennium as more similar to each other.
I mean, we always say it right, smart phone kids. The rapid rise of technology has created a stark division between age groups that isn't accounted for in the common definition of millenials.
I have two older siblings and one very younger. By some definitions, we would all be millenials. Of the older cohort, we were all born in the 80s, my younger sibling though was born in 2001.
I remember when the I remember the NES being a luxury in my childhood. We were early adopters of a home PC too, but even that was extremely time limited for us kids. We would be pushed out the door and told to be home when the street lights came on. We still brought that into our teens, and would wander around the city after (and during) high school.
I'm not really sure that my younger sibling even leaves the house if not for school. Kids born in the 90s would have been born into computers being an every day item, taken for granted. Video games that are far more complex and consuming with the advance of consoles and PC games.
Ranting now, but I know what it was like to watch technology develop, but I'm lumped into a generational definition with kids who grew up embedded in it. I think that has shaped us very differently.