What is the difference between “root cause” and “direct cause”? (Please note that I am only using the single tense of these terms in the question; I am not implying these causes can only be singular.)
But I tend to see a lot of “direct causes” being tagged as “root causes,” and in my eye, they can be and typically are vastly different.
Example:
a pleasure craft (boat) sank, killing both parties on board. Authorities stated the drain plug was missing from the boat when it was recovered. Neither occupant could swim, and the boat was not equipped with floatation devices. The accident occurred at a remote boat ramp at 2:35 a.m. There were no witnesses to the accident. Autopsies confirmed the cause of death was “drowning” for both of the deceased occupants.
Can you identify the “root cause(s),” direct cause(s), and/or contributing factor(s)?
Hint: some are obvious, and this is a trick question. 
Here are the official definitions that may help:
