The hammer and the screwdriver

Some people are like a hammer. They see nails and hammer them down or pry them up. Other people are like a screwdriver. They see screws and can screw them in or tighten them or unscrew the screws.

The hammer cannot work on a screw. It's useless or damages. Different tools are for different tasks. A screwdriver is of no use for driving in or removing nails either.