Dulce de leche is made from cow's milk, while cajeta is made from goat's milk. The process to make both is similar, but the milk is different, so they are not the same. Cajeta has a more distinct flavour coming from the milk. By the way, dulce de leche is also not the same as caramel sauce because to make caramel, the cream and butter are added after cooking the sugar, on the other hand for dulce de leche, the sugar and milk are cooked and caramelized together.