What is difference between Archimedian spiral and involute of a circle?

Can you tell apart the two curves? Since both the curves can be drawn by unwinding a string around a circle?

This picture shows both curves; red is Archimedes’ spiral and black is the involute of a circle.

On these pages Archimedes’ spiral and involute of a circle, can you explain following statement?

The Archimedes’ spiral is the pedal of the involute of a circle.