screw thread pitch

They even come with larger heads.

Use fine thread when screwing "into" hard woods and coarse threads when screwing "into" soft woods.

Use the larger head screw when attaching soft woods to either hard or soft woods and smaller heads when attaching hard woods to either hard or soft woods. Actually you can use a larger head screw on any application EXCEPT when using the shorter 1" screws. When using the shorter 1" screws the head of the wide head will still be exposed above the surface of the pocket hole.