What were diferences between George Washington, John Adams, and Thomas Jefferson?
I would say that there are two major differences that we can look at here.
First, Washington and Jefferson were rich landed gentry from Virginia. They were people whose wealth came from the plantations that they owned. They were slaveowners. Adams, by contrast, was a lawyer from Massachusetts. He was well off, but he was not a major landowner or slaveholder.
Second, Washington and Adams were Federalists while Jefferson was an Antifederalist. The first two presidents tried to make the presidency seem like a very dignified and important office. By contrast, Jefferson tried to seem more like a common person (the Federalists were more of an elitist group) by doing things like walking around instead of being driven in a fancy carriage.