Star-off Sneetches
These Sneetches are a metaphor for those that are outcasted from society. Indeed, much like humans, Sneetches seem to have devised a class system. Those that are fortunate enough to be born with stars are considered to be superior.
Sylvester McBean
Sylvester is a metaphor for those that are opportunistic and seek to gain profit at the expense of others misery. He does not care about how the star-off Sneetches feel and simply exploits them for money.
Star Machine
The machine is meant to be a metaphor for life having no quick fixes. The Sneetches without stars think that this machine is so powerful it can change their status but all it does is leave them the same because it is then considered special to not have a star.
Sneetches in the end
The Sneetches in the end are a metaphor for a lesson learnt. Despite McBean claiming that 'Sneetches don't learn', the Sneetches do in fact go on to apply what they have learnt from their actions and go on to live happily with each other.