Production is very different between Allies and Japan
Allied side gets deliveries of airframes with the exact amount and timing predetermined at game start. Some of the production is done on map by the factories in some of the allied bases, mostly big cities in US, Canada and Australia. This means that if those factories get damaged or destroyed by Japanese player, production will suffer accordingly. Allied player can repair damaged factories but can never expand them larger than at game start. Other part of allied production is completely off map, and can't be changed in any way
Japanese airframe production is a subject with steep learning curve and high probability of wrong decisions reflecting on the success of the entire campaign.
Japanese player gets to decide which engines and airframes to produce and which of the future engines and aiframes to research to bring forward their date of arrival. Airframe factories are located in Japanese cities mostly on the Home Islands, and come in two types: production factories and research factories.