When should you counterbore a hole vs counter sink a hole?
Holes, it sounds very basic but there was a lot of engineering put into the design of holes, screws, and the necessary clamping force for different applications! You really don’t want screws to come loose in critical safety applications. If you need an example, look no further than Tesla recalling cars for a loose bolt.
Though for most applications, both are effectively the same, countersinking has an angled profile whereas counterboring has a flat profile. Because of this, the connecting force is directly perpendicular for the latter meaning it provides a stronger connection. On that basis its more appropriate for heavy duty applications where this may be a concern.
On the flip side, countersinking is faster to do. So that’s its pro.
Counterboring also typically requires more space so where that may be a concern (designing small PCBs or aesthetics are high priority) countersinking may be the desired choice.