The TV version of the story largely skims over the details of George's backstory, from how he became king to how he feels about much of the goings-on. It's not until the fourth episode that we flash back and see the events of the first three episodes again from his perspective, and the "point of view" of the show mostly remains on Charlotte.
In the book, however, George's voice is present from the beginning, with many chapters written from his point of view. We learn more about exactly how his family story unfolded, including his father's untimely death (hence why his mother, Augusta, is a princess, not a queen), his terrible grandfather, and more. We also, heartbreakingly, get inside his tormented mind and heart from the very beginning, giving more insights into the lengths he will go to in order to "cure" himself of his illness.