China seems to prefer using 5.8mm for short and medium range use and lightweight 12.7 mm weapons for long range firepower.China has been an interesting case in terms of Machine guns. An M249 is a SAW (Squad Automatic Weapon) normally a belt fed weapon using the same ammunition as the standard rifleman. Light, can put down a high volume of fire but not really designed for sustained, long range or static mount firing.
GPMGs (general purpose machine gun) are heavier, use a full power rifle round, and are better designed to provide long range, sustained fire possibly in a static mount.
Now China's current standard service machinegun is a GPMG, the QJY 88 uses the 5.8mm round (albeit a heavier powder and projectile load) rather than a full power rifle round. The PLA's SAW is the QBB 95 also using the 5.8mm.
Since the PLA use 5.8mm for both SAW and GPMG the distinction isn't and has never been clear. This new MG could be used in a SAW or GPMG role depending on its configuration, i.e barrel length, static mount, bipod etc. This line would be further blurred if the PLA decide to replace the QBB 95 with this 5.8mm MG (makes sense with the introduction of the QBZ 191).
simple answer is: as per Chinese MG doctrine of not using full power rifle rounds and sticking to 5.8mm for all their squad small arms, the new MG could either be a SAW (M249) or GPMG (PKM, M240) according to the part configuration it operates in. Key difference being the ability to provide long range (long/short light/heavy barrel?), sustained fire and use in a mount.
Does PLA have firearm chambered in .338 Lapua or something similar for long range sniping or they just rely on 12.7x108?