If it is oem stuff, some oem stuff is made to a lower spec at request of the bike manufacturers to cut cost.
For instance an oem fork manufactured for a bike company may have a steel steerer instead of the alu steerer that comes with the otherwise identical aftermarket fork.
My recent xt shifter purchase, the indicator window is slighty smaller and squarer and shifter body is slightly a different shape with no cover included to cap the gap left if I choose to remove the indicator.
Is this an oem part that was made this way in order to shave a few pence of each unit for the industry or have they stopped making all xt shifters as the ones I already had that provide the cover plate.
Because to make both at the same time to be sold as an after market product as the same product rather than clearly two different versions of a simmilar product and not making this clear when purchasing would leave a lot of people feeling cheated.
Not all oem stuff has had corners cut to save money, and some that have the corners cut may not effect operation, but in some cases it is not just the fancy packaging that is missing.