Whats the differens between 0800-023100-0001 and 0800-023100-0002?

And this with arrows on wrong direktion and everything. 

[2015 Z Force 800 53/Trail EPS]

If the parts chart shows only one set, most often the difference will likely be one will be for cylinder #1 and the other for cylinder #2. The marks or arrows MUST point in the proper direction as the wrist pins are not in the dead center. If a parts chart shows the same number for front and rear but two different number sets, it's likely one set is oversized for a rebuild that required boring. Consult the service manual for clarity.