They sure look the same.
First of, I'm a total n00b!
To ease talking about the pins I made a pic where I numbered them, no idea if this is a smart way of doing it.
I think all you need is a multimeter to figure this out.DO NOT TRY THIS UNTIL SOMEONE WITH MORE KNOWLEDGE SAYS IT'S OK, YOU MIGHT DESTROY THE pH METER
Do I remember correctly that the meter gives randon mesurment(numbers jumping everywhere on LCD) when it NOT submerged in anything? If so:
Try measuring the pins (might be easiest at IC end) against ground, while its NOT submerged but ON.
If you get a voltage on almost all pins(we are not looking for a constant voltage, just quick pulses, as the numbers on the LCD randomly change), that would mean the LCD has common ground. Note/post the voltage. Note/post what pin/pins are 0V at ALL time, that would be ground.
If not(or only at 1 or 2 pins) it would have ground at the pins and voltage as common. Shit, I cant imagine this helping you a bit, but... I'll go one...
Lets say you get 3.3v at almost all pins, so we have com ground.
Now turn of the pH meter and take 2 of the 1,5V battery's and connect BAT- to lcd ground pin. Then connect BAT+ to 1k resistor and to LCD pins(one by one) that gave you a voltage when testing before. The 1k Ohm might be to big and the LCD segments dont light up, then you would need to change the resistor to a smaller one. Actually, I'm not even sure if you need a resistor. Oh god, this is not going to end well...
If you get the LCD segmets(you should see just one light up at a time), take note what segment lights up and what pin at that time you are applying voltage to.
Now we would know what combination of pins for example are on/high when the LCD is displaying 1.1. This way I think you could connect the LCD pins to digital input pins(or piso) and get the reading in to your arduino.
I'm totally guessing here, I DO NOT KNOW WHAT I'M TALKING ABOUT so please, help out.