I'm creating a standing rule:
One may not be given the title of 'legend' until 20 years out from their debut album, 15 ABSOLUTE minimum and only for special cases.
A legend is legendary. They are highly revered and esteemed throughout generations. An icon is easily recognizable or symbolic. Simple.
Nicki is an icon for female rappers at this point. Is 50 Cent a Hip Hop icon as well? I will say yes.