What is the difference between the Athenian maritime power and the maritime union of the policies?

The Athenian naval union, which was organized to repel the Persians and return the territories seized by the Achaemenid power in Asia Minor, went through two stages of development. During the first stage, it was a complex formation, consisting of many polis, and called the Delian simachia (478 – 455). The main task of this union was the liberation of the Aegean islands from the Persians. But after the strengthening of Athens, this alliance was transformed into the Athenian state, where the top of Athens ruled alone. In 454 BC. the treasury of the former union moved from Delos to Athens.