Say you have a EMV card with a mag-stripe on the back.

On an unattended kiosk, the chip reader and the mag-stripe is the same dipping slot. So you don't know that as you're doing the dipping motion of the card into the slot, there's a skimmer that's reading off the credit card number from the mag-stripe. And most slots require you to dip the card all the way deep, which is very plausible for the full length of data to be read from the mag-stripe.


The live in-person transaction terminal, the mag-stripe and the EMV chip reader are two different slots on the same machine. There, you can see in person that the EMV chip slot is being used, that being the card sticks out a bit; with no way of capturing the full length of data stored in the mag-stripe. In contrast, the swiping action for the mag-stripe reads the entire data stored on the back of the card.