Segment display – Why selecting segment by GND
This is quite normal. Segment displays like that are usually available in both common anode and common cathode types. What you originally had was a common cathode type. What you have now is a common anode type.



Common anode displays are sometimes preferred because you can easily drive them with a darlington driver array, like the ULN2803:



The ULN2803 can sink quite a lot more current than a microcontroller GPIO pin, and so drive large, high brightness displays.