Many of those Chinese bikes require an inner spacer between the bearings on each wheel. This prevents you from over-torquing the axle bolts and damaging the bearing. The center of one bearing pushes against inner spacer, which pushes against the center of the other bearing, so no radial load is felt on the bearing race.
Also, the two bearings OND posted have different measurements from outer bearing case to center hub. If your outer spacers were set up for one bearing and you use the other bearing, they will no longer fit like they did. That also applies to that inner spacer.