Lockerbie bombing - amount of debris (confusing numbers)
Pieces of wreckage implies a large 'section' of plane, whereas debris suggests miscellaneous smaller items and bits of metal etc.

I agree it's potentially confusing, however, and likely arises from two people editing the same section without adjusting the context.

I'd say that 4 substantial sections of plane were found, along with a large amount of smaller debris scattered around, totalling around 10,000 pieces.