They don’t necessarily have to be classified as the same contributing factors. The de Haviland Comet may have failed due to our lack of understanding of metal fatigue with a pressurized cabin. That was engineering ignorance. If a manufacturer did the same today, it’s negligence because those are known engineering principles.
Boeing was knowingly not following their own procedures for safety critical design. They also admitted to conspiracy to circumvent FAA oversight. Which of the above categories would you put those in?