Dear Tony,
Yes - you got it right, same kind of nut, but different age. About WWII - a sterile drip is the see-through plastic bag with a nourishing liquid that doctors or nurses will then connect to your body (normally your hand) when you can't eat. So if the WWII thing is correct, they used coconut water instead of the usual sterile (bacteria free) solution to feed directly into the patients' blood. It is certainly nourishing enough, and in some countries the coconut is the main source of nutrition - much like rice is in other countries. It can be main ingredient in a multitude of recipes and depending on how you treat it, you would never know it all came from the same plant.
Regards, Susanne