I am planning to use Gregory Mankiw's Macroeconomics (not to be confused with his Principles of Economics) for self-studying macroeconomics, along with David Weil's Economic Growth. As you can see, Greg Mankiw's macroeconomics textbook is currently in its tenth edition. However, the only copy I have is of the fourth edition.
What are the differences between the two editions? Specifically, are there new topics that have been added (if so, how important are they for a first introduction to economics?), major additions to existing topics, or topics that have been removed entirely?
My background is that I am currently reading Hal A. Varian's Intermediate Microeconomics: A Modern Approach and working through his Workouts in Intermediate Microeconomics.