Strictly speaking a credit card is a "carte de credit", however between the simple translation with english, the similarities between the form factor etc, A LOT of French (especially not used to the US credit card) will call their debit card 'carte de crédit'
Their is a lot of confusion on this, but most of the time french people use debit card. In fact I think banks almost don't advertise credit card, only companies offer this (airlines/supermarket)
On the technical side, there is no difference most people have visa/mastercard
