Putin was and is the same person and the reason of its behavior wouldn't required at the Bill Clinton or George Bush (which are both USA presidents and as such the same kind of people) but because at the beginning Putin was a puppy and had not the possibility and the power to play the "world leader". Then day after day he put on display its true character and personality constructing its "glory".
Putin never wanted to play the role of the "world leader". That distinction is reserved for the American presidents. Putin just want to retain the Russian influence on various ex-Soviet states (such as Armenia, Georgia, Ukraine, Moldova, Belarus, Kazakhstan, Uzbekistan.etc). He is not interested in the area outside the former USSR, as evident from his lack of interest in the events happening right now in Cuba and Venezuela.
Putin wants to uphold and restore Russia to a position of strength. It has always been the way of Russian Communism to take over the world, just the same as Islam, and many other national themes.
The United States is taking over the world by offering the people way more freedom in general than any other nation does. In other words, Americans are taking over the world for the United States.