It need not be a higher standard, it is a different philosophy of creating the "list of stuff we need".
One is part number oriented, without considering how material arrives. One is material oriented, in that it considers how much material is required, including details of how material comes in. Yes that is very simplistic, and there are many other issues.
The bill of materials shows the quantity of each part number needed to make the item. It is no particular help with how much 16mm shafting must be ordered given that it comes in 5 metre lengths.
SOMEONE has to figure that out so that material can be ordered, regardless of whether a "higher" or "lower" standard is held to. The typical parts list provides that, in addition to showing in what form the stuff is used (part numbers). And other things, of course. "So much of this material, fabricated into those, and used in these".
The true parts list is a list that can be directly given to a purchasing agent who can then buy it and know that every material item needed to make the product has been ordered. It does not necessarily mean that what is bought is used directly in the form in which it arrives on the dock.
The "bill of materials" usually is composed of finished parts that are used directly, although some BOMs are hybridized if part numbers are not assigned to some cut bulk materials. So there may be fibre insulation listed as X number of feet, or metres, etc, simply because the stuff is cut to fit as it is installed on the assembly line, and specific numbers are not assigned to each cut piece.