Difference:

Genco Olive Oil Company and the early days of GF2 are in Hells Kitchen, NYC (Around West 34th-39th Street and 9th/10th avenue) in the Book, but in Lower East Side, NYC in the film (around West 2nd-6th St). (Puzo grew up in Hells Kitchen).


Roberto the landlord returns to Young Vito's home in the book, and to Genco Company in the film.