I still think my definition holds true... perhaps let me explain.
Different is obviously, the opposite of "same." I'm quite sure that this is undeniable (if you have a "different" meaning for "different" *pun*, then... just skip my post) Everyone else who posted on this thread is also supporting this, by suggesting some of their character that sets them unique from one another.
However, different is an adjective. It compares something to another. Well due to the nature of this thread, we're comparing people to people, and seems like it's yourself to others looking at the type of posts coming from the others within this thread.
The true question is not "what makes people different." Like what Chairman Kaga said, "everyone is different," because no one was ever created completely alike one another. We're not robots under mass production, and even twins are different from each other a bit. Let the question be: "Who are we comparing ourselves to?" Adjectives are comparison between one thing to another. Well seems like we're comparing ourselves to other people. But who are "other people?"
If I compare myself to Dizzy for example, we're quite different in many ways. I dislike parties, shopping/going to the mall and techno music, while he likes them all. I'm a christian, while he's gaiaist (sp?) and a roman catholic. However, we're the same in terms of going to PC, liking Pokemon and games. Now if I'm to compare myself to 22sa, then there will be other differences and other similarities.
Therefore, how the heck is this question suppose to be answered when there are "different differences" depending on who we're comparing to? Unless the answer you're seeking for is "everything," then nevermind... So human beings being so egocentric as we are, just set the "standard" as the majority. Afterall, "majority rules," hmm? Plus the majority's liking is set as standard, because since it's the majority, most people will know about it because it will be everywhere around that person unless you live in a cave/never go outside like me except for school and church. If everyone knows about it, then it can be set as the standard thing to compare "differences" to.
So now we all understand that differences are compared to the majority unless otherwise stated (which in this case, it is not stated.) People get together and have an easier time communicating and befriending one another if they have more similiarities. This means that the people will have more to talk about, and arguments are less likely to break out because there are higher chances of a group of people coming into an agreement instead of an argument if they are similiar (such as personality and character, and even race, and yes racism does exist even though theortically it shouldn't) So usually, people with similar traits go together and form their own circle of friends, while other people with other traits go together with others who have the same trait as they do and form their own circle of friends. PC works the same way too, as we all join together because we are seeking people with similar interest on the board.
Popularity is defined by just how big this circle of friends are, which is formed by the majority. You're an outcast, or is unpopular, if you belong to one of those smallest circles because there aren't that much people who has the same trait as you.
Summing up EVERYTHING in this post, we come to the conclusion that popularity does equal to similarity and differences. If you're unpopular, you're "MORE different" than others in comparison to the majority. No one can be exactly alike to the majority standard even if you're popular, but you're certainly more different than the majority if you're unpopular.
Hope that made sense, and hope Dakota won't take offense of this too ^_^;