I know generation is a tricky, subjective business, and I want to add a disclaimer that I am expressing my educated opinion according to what I have studied, and I am not attempting to "police" the generation forums, as I too had some early questions about Gen X v. Gen Y, and now there appear to be Y/Z issues.
Characteristics of Gen Y include growing up with more technology than Gen X but not as taken for granted as Z. We grew up with more commercialism and corporate BS and branding than Gen X. We are more likely to have "gold star" syndrome or narcissistic traits.
Part of the reason for our narcissism is being able to remember a pre-9/11 world where we were given everything, sheltered, and promised as long as we went to college, we could have ANYTHING, then had our entire childhood snatched away from us, leaving us feeling both exceptional and cheated, having to adjust to a more realistic economy and having to pick up the pieces from what we enjoyed in our childhood.
9/11 is the major political event of Gen Y. It is part of what shaped our psyches, as well as 80s/90s childhoods among affluence and American exceptionalism.
Gen Z on the other hand has no or unclear memories of 9/11 and can't remember the 20th century and had a childhood in a tougher economy during a time of war when America as an empire was mocked and challenged.