Confusingly Primitivo and Zinfandel are the same grape. As for why they have such wildly different names is because it has had long histories in two main countries, and an even longer history in its historical home of Croatia where it is known as Tribidrag, without anyone knowing they were the same grape until recent DNA testing proved they were. As such, you have the Primitivo of southern Italy that tend to be fruit-forward and the Zinfandel of California which tend to be a bit spicier and oak-predominant in flavour. Irrespective of where it is planted it has a wide range of black and purple fruit flavours.