I forgot to mention his looks, which are very different. From the wiki:
"Ramsay is an ugly young man, even when dressed finely. He is big boned and slope shouldered, with a fleshiness indicating he will be fat later in life. Ramsay's skin is pink and blotchy, his nose broad, his hair long and dark and dry. Although his mouth is small, Ramsay's lips are wide and meaty, wormy looking, and he smiles a wet-lipped smile. His distinctive eyes resemble Roose's - small, close-set, and oddly pale, like two chips of dirty ice."
Google "ramsay snow book" to see some artists' interpretations of him. It's all so incredibly different than the show Ramsay, who was likely picked for the role because he wasn't ugly and could read lines in a sinister way. Classic Hollywood, casting people who don't resemble their characters at all because sex (appeal) and smiles sells.
@Olaf Read away if you feel like it. This point onward you can read every book currently out and there will likely be no spoilers for the following seasons, since they altered them so much. You'll see what I mean if you do read them. As for the upcoming books, the next one is going to likely share some similarities with the next season but be overall very different, while the following and last book will likely be out in several years if ol' George makes it that far, Deus Vult, which will probably be after the show ends.
Unrelated: I got A World of Ice and Fire for Christmas, and I've been reading short chunks every day or other day. The story of the Rhoynish Princes vs. Valyria and Princess Nymeria could totally make for a great movie. I'm sure HBO will keep the GoT train rolling after the main series is over, and I really hope that's one of the things they do, maybe as a mini series if need be. I can imagine them keeping the story exactly as it's told, with all the crazy magic shit that might not have really happened, and end it with a Princess Bride esque ending, where a Maester or nan or whomever finishes reading the book to some Westerosi noble kid (Old Nan and Bran would be iconic for HBO fans). That way they can barely tie it to GoT and focus on a good story, and still bridge the connection at the end to make sense of the questionable points of the story, like the magic/curses and the amount of ships Nymeria had.