Salim and the Jinn are Involved in the Main Story
The story of Salim and the Jinn was one of the many one-shot Coming to America stories in the original American Gods novel that helped to establish the setting apart from the main plot. In this tale, an Omani Muslim immigrant named Salim, who came to America to work as a salesman for his brother-in-law, has a chance encounter with a cab driver whom he recognizes as a Jinn - one of the spirits of fire from the myths of his homeland. The two share a night of passion, after which Salim finds himself given a chance to make a new life free from the burdens of his old existence when the Jinn leaves behind his cab keys and identification.
This scene is faithfully reenacted in American Gods season 1. However, Salim shows up again later in the main story, as the cab driver who is recruited to drive Mad Sweeney and Laura Moon to Kentucky. Along the way, Laura and Salim talk about the power of love and Mad Sweeney offers Salim a tip on where to find the Jinn, whom Salim still dreams of and hopes to find again.
Salim finds the Jinn in the American Gods season 2 premiere, where the Jinn is overseeing the security for Mr. Wednesday's meeting at the House on the Rock. We don't get to overhear much of their conversation, apart from the Jinn trying to warn Salim away from chasing after him and Salim insisting that his heart is set on the Jinn. We later see the two sharing a meal together at the diner before the New Gods attack, though it remains to be seen how their relationship will progress over the course of American Gods season 2.
The New Gods' Attack on the Diner
The most significant change from the book comes at the end of the American Gods season 2 premiere. It's here that the New Gods attack the diner where Mr. Wednesday has gathered several of the Old Gods in order to recruit them to wage war on the New Gods of America. The altercation ends with snipers killing several innocent mortal civilians as well as the Slavic goddess of twilight, Zorya Vechernyaya. The New Gods also kidnap Shadow Moon, who is spirited away in a craft that resembles a UFO.
While there's an attack on the Old Gods meeting place in the original American Gods novel, the exact details aren't described. Whereas Shadow gets to enjoy a meal with the gods in the television series, he is jumped before he can enter the restaurant in the novel and nothing is said of precisely how he is taken to a New Gods secret base. It's also said in the novel that none of the Old Gods died during the assault, where as Zorya Vechernyaya is explicitly confirmed as dead in the American Gods season 2 premiere. This should raise the stakes significantly and bring more Old Gods in to join Mr. Wednesday's war as the story continues through the second season of American Gods.