Flat irons and crimping irons are similar yet different. The only difference is that the crimping machine has ridges on the surface of the heating plate. These ridges provide your hair with a crimped look. Whereas straightening, straightens the hair, even the natural curls vanish, and hair appears to be straight. Crimpers require holding of the two sides of the plate at equal intervals to have a crimped look. On the other hand, a straightener glides smoothly through your hair.