Why Kreg Pocket Hole Screws are better:
About the Maxi-Loc? Head:
Kreg's most common screw head type is the Maxi-Loc? (SML) which is a washer head screw. The large bearing surface of the washer head is designed to seat securely in the bottom of the pocket, providing a tremendous amount of consistent clamping force on the joint line. Our second head style is referred to as a pan head (SPS). The pan head is a slightly smaller head size that allows it to easily get below flush when joining 1/2 material. This is particularly helpful when joining 1/2 to 1/2 plywood for drawer boxes.
Coarse thread is good for harder woods.