In a Ponzi, person B still has a claim on the money, despite it having been fraudulently distributed to A.
When company earns profits from customers (B) and then gives those profits to shareholders (A), B no longer has any claim on the money.
That is the difference.
Now it is possible that some companies are indeed Ponzies, where earnings are nonexistent or overstated, and money from other investors is misrepresented as earnings, but that is not the general case.
Look no further then into your back pocket and pull out one of them crisp bills And ..Voila the great note of the Federal Reserve. The biggest Ponzi scheme ever. So big even Charls Ponzi him self would be in shock that they pull the wool over the publics eyes on this one. It makes me laugh when people say steemit is a scheme, yet they rely on the fiat currencies of central bankers.
I say if it's got trust it has purchasing power.