Titanic was 3 hours long, of which it spent a lot of time focusing on characters besides the two "star-crossed" lovers (for example, the captain, the architect, the Irish immigrants, etc.).
And although it skims over parts, like when they stopped off in Ireland, it's pretty accurate and it doesn't glorify the deaths of the passengers for entertainment. Also, the film's makers made an accompanying feature-length documentary (Ghosts of the Abyss).
This DW episodes however is purely for entertainment. They even have the same disasters happen (in this case the ship is hit by a meteorite, instead of an iceberg).