Traditionally, only when an actor achieved a certain standing in the film industry, was he/she called a star.
Ironically, we have more stars than actors today, as just appearing in a film seems to entitle one to the label of a star. Similarly, here's an incident concerning Riya Sen.
Apparently, a couple of months back, when Sen was good friends with Bobby Darling and they used to hang around in the same group, Bobby, was at Sen's home once when she got a call from some friends and curious by the noise around him, asked his whereabouts.
When Bobby said he was at Riya Sen's house, Sen threw a fit commenting how dare he drop her name just to show that he was good friends with the star and hung around at her place. But real stars know how to treat their friends and they don't treat even their less famous acquaintances like that.