Key specifications show notable differences: the 777-9 is longer (251 ft 8 in vs. 242 ft 5 in), has a wider wingspan (238 ft 10 in vs. 212 ft 7 in), and seats more passengers (426 vs. 365). Both aircraft share a maximum takeoff weight of 775,000 lbs, but the range of the -300ER slightly exceeds that of the -9.
A significant change comes from engine upgrades. The new General Electric GE9X engine on the 777X replaces the GE90 used on previous models. According to John Slattery, Executive Vice President and Chief Commercial Officer of GE Aerospace: "It takes the world's best talent in jet propulsion to create a game-changing product like the GE9X engine. There is no substitute that can achieve the combination of size power and fuel efficiency of the GE9X. This engine will deliver unsurpassed value and reliability to our airline customers." These improvements are expected to make the new jet about ten to fifteen percent more fuel efficient than its predecessor.
Further differentiation may come with future variants such as a proposed stretched version—the Boeing 777-10—which would add even more seating capacity and length compared to both current models and competing Airbus jets. Additionally, non-commercial versions like the BBJ (Boeing Business Jet) offer options for private or corporate use.
As for when passengers will see these advancements firsthand, Boeing expressed confidence at the Paris Air Show that deliveries would begin in 2026. Justin Hale, Customer Leader for Boeing’s large twinjets and freighters division said he is "very confident that the airplane can enter service in 2026." However, some customers remain skeptical; Emirates has indicated they do not expect their aircraft until at least 2027 or later due to their position further down Boeing’s delivery schedule. Hale addressed this by saying: "Emirates is not our first delivery airplane [ie inaugural customer], so when they talk about their airplanes coming in 2027, they're not at the front of the delivery stream and that was their choice of positioning. I think it's very important to be able to sit down with them and we do, regularly, with all of our customers, and talk about the progress we are making and the status of our certification work."
Currently there are over five hundred orders pending across all variants of the new model as airlines await delivery before these updates become available on commercial routes.