Puffball is used as an informal term for the members of the family Lycoperdaceae, which all start out with white gleba that becomes yellow and squishy, and finally dries up and becomes powdery and dark brown (or, in one case, purplish).
Earthball is an informal term for the members of the genus Scleroderma, which have a harder gleba that also starts out white, but quickly turns purplish-black. The toughest a puffball's gleba gets is when it's still very fresh and white inside; but even then it's not much tougher than firm tofu. An earthball's gleba is more like a tough cheese.
Some desert puffballs have a stalk, to keep the developing spore mass away from the hot sand. There are also beautiful temperate stalked puffballs in the genusCalostoma, but their stalk usually remains underground.