Except it doesn't matter how you want to think of it, when the way it's stored is the way I described it. The formats are designed to be backwards compatible, so If you lop off the last 8 bits of each word of a 24 bit recording (say by sending a 48/24 spdif signal to a dac that only supports 16 bits, it decodes properly. 24 bits provides the same resolution, with more headroom. In video, more bits = more resolution. In audio, more bits is just more bits. A 24 oz bottle holds 8 oz more water than a 16 oz bottle, but the water itself isn't any different.