It's a really terrible article, at least for the title. The answer is that split scimitar is apparently a bit more efficient. Sufficiently more efficient to be

It's a really terrible article, at least for the title. The answer is that split scimitar is apparently a bit more efficient. Sufficiently more efficient to be worth the change. > Split scimitar winglets are named for the curved Middle Eastern sword, extending above and below the wing, and ending in sharp points. They have been found to produce up to 5.5% fuel savings per aircraft, an improvement on the 3.3% savings provided by blended winglets. That's the reason, the rest of the article is fluff meant to keep people on the page and seeing ads because it obscures the answer they came to see.