Sparta, located at the extreme south of the Balkan peninsula was favored by its landscapes. Possessing large areas of fertile land, it had a self-sustained agriculture, and could afford having restrict commerce policies. Therefore, they did not depend on sea commerce to survive.
Athens, on other hand, was marked by uneven landscapes, unfit for farming, therefore depended a lot on commerce and because of that, expanded its trades throughout the Aegean Sea, with the islands and coastal cities around it, that would benefit greatly from this.