Also keep in mind, especially for A320neo, there are airlines with 400+ on order that may not all get delivered from both manufacturers.
Interesting who and when decides that an order logged in the books "may" not be delivered. Not surprised by the criteria applied seeing the numbers though.
Both Airbus and Boeing log orders that don’t always turn out. Them having a larger order book is in their interest. Airbus generally the worse offender. For example the Iran Air order has been booked by Airbus but not Boeing and likely to be cancelled within the next few months. Among others have been ordered and removed with no real chance of a delivery. Also the 400+ A320neo on order by Indigo from an airline with a current fleet of 150 relatively new aircraft also seems dubious. If I were a betting man I bet they don’t take all those aircarft. A few other too but I can’t think of off the top of my head.
It might take several years before Airbus will remove IranAir order from order logbook just like Iraqi Airways order for five A310 despite the production line has closed for several years. Few more comes to mind Kingfisher Airlines A345 and A380, Virgin Atlantic A380.
Like what Prost have mentioned some airlines log a huge order to lock in favourable production slots and turn over their fleet every 10-12 years. AirAsia funneled some of their A320 delivery to its leasing subsidiary and leased back to mainline service, build up the fleet and sold off the subsidiary for USD1.18 billion recently.