Patents at work.

Before the patent on Phillips screws & tools expired, Pozidriv was launched which was different enough to be capable of a bit more torque.

Phillips was for mass-production, Posidriv for mass-production with a little more torque.

Lots of people who wanted that still waited until the Pozidriv patent expired before considering it.

The screws themselves are marked on the head with little ticks so you can tell the difference, but not necessarily the screwdrivers :\

It's good to have the right tool for the job, HP instruments used Posidriv in a number of places.

the type of screw head really doesn't make a difference when I'm hammering them into the wall, I've found xD