U know i am always conflicted with the word up-sampling because i kinda never liked the idea of the genuine term of it as a electrical/comp sci engineer. With anything that is up-sampled its the process of adding zeros to the LSB. Anything else that changes data is dithering.
Especially in the world of audio up-sampling purpose till today the engineering part of me has never grasps the reason why. I can understand remastering and rerecording at a higher resolution.
Can some GODS that have brilliant physics or PHD EEE or Audio God explain to me WHYYY?
Upsampling creates additional samples between the original ones (or more accurately, expresses the data with more samples than the original number). Increasing bit depth adds more zeros. And if resampling is also applied, the additional bits are usually not zeros.
To appreciate upsampling with proper interpolation, resize an image in Windows XP's MS Paint. That is what happens when nearest neighbour is used.
And, dithering does not change data. Rather, it attempts to recreate the original data better when the new format is unable to (usually due to lack of bit depth). You can see the effect of dithering on pictures printed by printers, with the shades of colors resolving into many tiny dots of high contrast when viewed up close. TN LCDs use dithering to try to reproduce 24-bit color with only 18 bits.
The same reasons audio editors work at 32-bit and image editors work with 48-bit source, are why upsampling and more bit-depth, above what human can reliably perceive, is being used on the consumer side.