A quick perusal of the Wikipedia article reveals that the sinking of Doña Paz was the result of multiple failures to follow the regulations governing how to operate the vessel in safe and conscientious manner.
But the Titanic is different in many ways. Aside from all the wealthy people aboard, many of whom died (probably the primary reason the Titanic is more memorable, sad to say), Titanic'screw was, essentially following the rules. But the rules were shit. Required lifeboat capacity was based on vessel size rather than passenger count, and the Titanic basically fell into the "X many tons and above" category. According to the law, she had more lifeboats than required. The wireless operator spent most of his time sending and receiving messages for the well-to-do passengers; the regulations regarding the use of radio were primitive. The Californian was only about 12 miles away from the Titanic, but her captain had gone to bed, the wireless was shut off for the night, regulations didn't require 24-hour operation of the wireless. And because the bursts from the Titanic's distress rockets lacked color (certain passenger lines used certain colors; the White Star Line, the operator of the Titanic, used, you guessed it, white bursts in their distress rockets), the crew of the Californian just assumed the rockets were not a sign of distress. There wasn't any ice patrol in those days, either.
Not to put too fine a point on it, Titanic represented a "sea change" in maritime law governing how to operate passenger liners with a minimum of acceptable safety. Titanic essentially wrote these laws. Doña Paz merely broke a bunch of them.
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