How was romes treatment in Carthage different from its treatment of conquered peoples in other wars

It was normal that the Roman general who defeated them wouldnegotiate the settlement with the Senate, becoming their patron andgetting the best deal he could. With Carthage, after two wars,where the resilient Carthaginians bounced back, Rome went for afinal solution after the third war, levelled the city and sold itspeople into slavery. It then established a colony of retired armyveterans on the site to clinch the deal.