De IGN - Diferenças dos livros de TV :
Point of View:
- Since the plot in the novel is told from the viewpoints of the principal cast of characters, the show fleshes out certain key scenes that are either absent from the book, implied, or talked about in other chapters.
Character Names:
- Certain characters have undergone a name change for the TV series to avoid confusion.
Character Appearance:
- Certain characters within the series have been played by actors who do not share the same physical traits as the said characters.
- Some characters' races have been changed in the show as well.
Character Additions, Omissions, and Mergers:
e.g. Talisa of Volantis, a character not featured in the book, replaces Jeyne Westerling.
Some minor characters, like Alton Lannister are substitutions to help move forward key scenes that involve characters omitted from the show.
Certain characters had their fates altered and are killed off differently or earlier in the story.
Some characters introduced in book 1 or 2 are absent from season 1 or 2, respectively and may appear in later seasons.
[Click the link to see more examples/details, including a breakdown by season]
O Game of Thrones Wiki também tem uma extensa lista de diferenças: