The speed of the card affects the number of frames you can shoot per second; everything else being equal. Also, the quality of the picture is affected by the format used - RAW Vs JPEG - JPEG pics are 'processed by the camera's software and then stored/displayed as an image; whereas RAW is stored in pixel form and needs to be processed by the photographer much like a negative in film format.
The photographer has much more latitude working with the RAW format. Hope this helps.