Ditching in the north Atlantic in the middle of winter is entirely another.
It doesn't even have to be middle of winter. Hans Horrevoets was swept overboard from the Dutch Volvo Ocean Racer ABN AMRO II on May 18, 2006. He was found just 20 minutes later but CPR failed to revive him.
I don't know the details, but he was swept overboard by a wave while the boat was doing 20-30 knots or so, not involved in ditching an airliner at, what, 150 knots? So it is fairly safe to assume he did survive the initial impact in the water. Also, he had more or less suitable clothes on. Not a drysuit, not a lifeline, but sailors wear in any case. Something more suitable for survival than a business suit in any case. And these guys are very, very fit and trained for what they're doing. In fact, they're required to have undergone maritime survival training before being allowed to enter the race.
Yet he died, either from hypothermia or drowning, or both, in less than 20 minutes.
Now project this to an airliner ditching. Think about the impact forces of the "landing". Think about average clothing that's being worn on an aircraft. Think about how long it will take for suitable rescue to arrive, able to deal with 300+ victims. No chance at all for survival in the North Atlantic.
As far as the Egypt Air is concerned, what I remembered from the NG documentary is that they ditched very close to a crowded beach, in shallow and warm water. With the result that the fuselage bits did not get submerged completely and lots of pleasure boats were able to attend the rescue immediately. So a lot of the victims that did survive the initial impact did not subsequently drown or die from hypothermia. But I have to admit my memory is sketchy on this one.