Not sure what justifies the difference other than people not knowing about the other place. I have never tried Park N Fly, but am very happy with Vinci. The shuttle comes by quite frequently, the parking lot seems to be quite secure with license plate pics taken in and out, the staff are friendly.... And they always give 20% off! ^ In the winter they also offer a valet service where for $5 more they will clear off your car and warm it up for you when you arrive.