The present study tested whether the degree of phonological difference between the labels of categories influence category learning and generalization. For this purpose, two experiments were conducted. In the first experiment, participants learned two categories labelled with pseudo-words that were controlled for the degree of difference between the phonetic features of their labels, such that they each pair was maximally different, minimally different, or somewhere in between. These labelled conditions were compared against a no-label control condition. Results showed that participants learned faster and generalized better for categories when category labels differed more.In the second experiment we tested whether these effects could be attributed to the sound symbolic congruence of the labels to the category members. Results showed that phonological differences influence learning independently from the sound symbolic match. Further we specify a category learning model based on generalized perceptual discriminability of the to-be categorized information, including perceptual features of both items and their labels: Categories are easier to learn when their features (including labels) are easier to discriminate.