Screwdriver tip type must match the fastener. Phillips has a cross recess that cams out under torque by design. Pozidriv looks similar but has additional cross marks and does not cam out — using a Phillips driver in a Pozidriv screw damages both. Slotted (flat) tips come in different widths and thicknesses and must match the slot. Torx and hex (Allen) have six-point engagement and tolerate higher torque without cam-out.
Tip fit is the specification that matters most. A tip that is too small for the fastener will round the recess; one that is too large will not seat. Precision-ground tips fit better than cold-formed ones.
Hex keys are sized in fractional inch or metric and the two are close enough to be confused — a 5 mm key is a loose fit in a 3/16 in socket. Ball-end keys allow access at an angle but transmit less torque. T-handle and folding sets are convenient for repeated work.
