While there are technical differences, your Lightning to USB Type-A (iPad Air2) and Lightning to USB-C (iPad9) cables are essentially the same for data and charging your iPads.
USB Type-A is now a deprecated standard - having been superseded by USB-C. Many newer computers now only have USB-C ports (potentially providing much faster data transfer - and wider support for other services).
All USB Power Adapters and charging cables are moving rapidly to using USB-C. Many countries/regions (e.g., European Member States) now mandate use of USB-C for portable electronic devices. Manufacturers now have a relatively short period within which to ensure that new products comply.