The depth of Key press. The previous keys on Macbook are 1.5mm in depth, the distance it travel every time you press it, with roughly 60g of force. This has been sort of the golden standard in keyboard on Notebook ( and in many cases Desktop ) for more than a decade. Apple reduce that to 0.7mm in their infamous butterfly keyboard in the name of thinner devices. For some that might have been fine or even preferable. For many its typing experience is much worst.

Due to its reliability problems ( which may not have anything to do with the lower key depth ) Apple walked back on the design and uses a 1 mm Key travel "Magic Keyboard". And from my experience it is pretty much the same as the old Butterfly keyboard in terms of Typing experience.