What is the difference between hair curled by a straightener and a curling iron?

I'm pretty certain the answer to this question is rather.... obvious. But here goes...

A straightener is supposed to heat hair so it becomes malleable. So as you run the straightener through a set of strands, the hair is heated and straightened by the motion you put the strands through. If you twist and spin the straightener while running hair through it, you can instead bend the hair by heat and create a curled look.

Hair curlers, on the other hand (not literally), have a wavy design that is meant to create alternating curls. They're not really "curls" per say, but just alternating bends that occur in a horizontal manner. And you simply use one doing row by row from top to bottom of your hair.

So, it's a matter of technique versus the tool you're looking for to get a certain kind of result or job done.