It is a branch that actually has mutated, and hence is a different variety, since it is different genetically, but not one that was produced sexually, via seed.
Panache is believed to have been a "sport" of a green fig many, many years ago, and frequently mutates back, presumably to what it was originally. They are also called chimeras, and are often unstable and revert back to their previous form Many variegated plants are "sports", originally.
In fruiting plants, the change may only be reflected in different leaves, or different tasting fruit, or more vigorous growth, etc.