Samsung introduced the Diamond Pixel display architecture back in 2013 when it launched the Galaxy S4 smartphone, and since then it has adopted this sub-pixel scheme in all of its OLED displays (replacing the previous PenTile scheme).
The 2014 Galaxy S5 introduced a different Diamond Pixel scheme which Samsung uses till today. DisplayMate tested the Apple iPhone X and it turns out that Apple's OLED, even though it is produced by Samsung Display, uses a slightly different Diamond Pixels - the fill factor of Apple's display is higher than in the Galaxy phones. You can see the two different displays in the macro photos above (courtesy of Display Mate). The iPhone X OLED is on the left, while the right shows the Galaxy OLED.