The correct answer is “Like Plato, Aristotle, wrote extensively on the subjects of tyranny and the rule of law.”
Here the author is saying that Plato and Aristotle both had views on tyranny, politics and government and that they both believed that the rule of laws are needed to protect against tyranny.
The main religious difference between the Separatists and the Puritans was that Puritans wanted to separate from the Church of England and form their own church. While the Puritans did not want to break away from the Church of England, they just wanted to make a few modifications in it. The Puritans wanted to reform the existing religion because they believed that The English Reformation had a lot of Catholic influence. Besides, both fled England to escape from persecution under the King's rule so the Puritans settled in Massachusetts and the Separatists settled in Plymouth Rock.