As the American colonies were run by and for the benefit of the English, political changes in the mother country inevitably had a knock-on effect on colonial government. One of the biggest of such changes was the accession to the throne of King Charles II in 1660.
During his reign, the old High Church establishment reasserted itself, unleashing a campaign of intolerance and persecution against religious dissenters. This meant that the colonies increasingly became a haven for those seeking to practice their religion in peace. In turn, this changed the whole nature of government in places such as Boston, which became the kind of Puritan theocracy which English religious dissenters had long dreamed of establishing in the mother country.
Meanwhile, in Pennsylvania, a colony was established by the Quaker William Penn on the basis of religious freedom and democracy. King Charles II was only too happy to grant Penn this plot of land in lieu of money he owed to his father, Admiral Sir William Penn; yet it's also likely that Charles saw the opportunity to be rid of subjects he regarded as a potential threat to his regime and its policies.