The Chinese claim a lot of things…
Unless they specified the specific 5.56MM cartridge that it was supposedly better than, it's kinda hard to answer that question. With 5.56MM, you have options.
Up-close and personal anti-personnel round that doesn't over-penetrate: M193
GP penetrator with better medium range ballistics: M855
Better barrier penetrator with better accuracy: M855A1
Better barrier penetrator: MK318 MOD 0
Better fragmentation envelope and distance and accuracy at distance: MK262
There are other rounds in inventory, like AP (uncommon), but you get the idea.
If you look at the barrel length that M855 is fired from, it becomes apparent why DBP87/95 or later variants thereof are superior to M855. The test barrel length for US cartridges is 20". The test barrel length for their DBP87 cartridges is 557MM or about 21.9". The cartridge is the just about the same in overall length as US M855, the bullet is only 2 grains heavier, and less than half a millimeter wider. How superior do you think that ammo could really be to 5.56MM? Chop that extra two inches off the Chinese barrel and see which cartridge performs better. MK318 already does 2900FPS from a 14" barrel and about 3100FPS from a 20" barrel. If DBP87/95 does 3100 FPS from a 21.9" barrel and DBP10 does 2900FPS from a 21.9" barrel, which rounds are they superior to? Can you chop 3.9" of barrel off of their guns and get the same velocity we're getting from MK262 MOD 1?
I'm a little skeptical of Chinese claims of producing superior ammunition or weapons.