A superstar must meet certain criteria while still being in their peak (hence there are vets who use to be superstars see Jordan at the wizards)
popularity i.e fame,shoe and jersey sales,peak brand endorsement etc
reputation i.e face of the league or consistently regarded as top 5 players in the league for multiple seasons
Accolades/body of work-this is self explanatory
the late 90's - early 2000's superstars were shaq,Kobe,Iverson,Duncan and KG
late 2000's superstars- Lebron,Kobe,wade,Duncan,Dirk
2010's Lebron, KD,steph,Harden,Kawhi