Carmelo Anthony is a great example of the pseudo-superstar. A pseudo-superstar is a player, perhaps even a legitimate All-Star player, that pretends to be a superstar. He gets called a superstar and wears the superstar disguise, but he's not a superstar.
A superstar is a player that can carry a team to elite status.
A superstar makes the players around him better.
A superstar plays on both ends of the court.
Carmelo Anthony is not the only offender here. There are other players who aren't superstars but have been called one at various times.
Admittedly, there is a degree of personal preference and experience here. How big of a star is a player? What makes a superstar? Is such and such player really considered a superstar by some? All of these are highly subjective.
At the same time there is a general consensus that's available just by being well-read on the NBA. The players are ranked according to how close they are to actually being real superstars; i.e. the top-ranked player is the closest to actually being a superstar although he is not one yet and the 10th player has a long way to go.