According to Chris Spear
The biggest change is that this edition can also be used as a textbook for an undergraduate or graduate course in verification of digital designs.
Once again, Chris and Greg have responded to feedback from readers, professors, and students about SystemVerilog concepts. Almost all of these conversations have been incorporated into this book as expanded explanations and code samples. Starting with chapter 2, most pages have been improved with clearer explanations and better code samples. There are over 40 new pages with new information on UVM concepts such as factory patterns.