To clarify juicetone's comment:
The 14.5 and 20 degree angles refer to the pressure angle of the gear teeth. This is the shape of the teeth. 20 degree may be marginally stronger than 14.5 degree but in my opinion the cam gears are plenty robust either way.
The zero degree refers to the helix angle of the teeth or sometimes called straight cut or spur gears. Spur gears should be stronger than helical gears but again, I don't think strength of this gearset is in question. Helical gears will exhibit axial thrust and will be quieter compared to spur gears.
