Microcasting is using a mold to fill it with liquid piston aluminium but under a high pressure. The molecules will be closer to each other making the material stronger. Finally this piston will be shaped by a CNC proces.
The CNC piston is just made from a bar delivered from the supplier.
Both are just piston materials.....
Depending the other materials inside (copper, iron, silicium etc) the specs/properties is determed like friction, strength, expansion rate etc.
So for me a CNC or a Microcasted piston is just a piston and only these words say nothing about the specs than only that the Microcasted must be stronger.