Need help finding pin layout diagram for GSM module (SIM800c RPi development board)
This is probably not the answer you are looking for, but those 2 boards are not the same. There are many different versions of the SIM800c breakout boards, and that means you cannot say for sure whether pinouts are the same with these 2.

This bit of the answer you may enjoy less, although it is good news in that you can figure it out for yourself! You can look up the DATASHEET for the actual module and get a pinout of the module. Using a multimeter set to continuity mode, you can test each pin until you get a beep. You can then draw your own diagram of a pinout for that board. If you wanted, you could then upload it here as your own answer in case anybody else has a similar issue with this board.

If you are only after the Tx/Rx pins for now, then those are just pins 1 &amp; 2 so shouldn't take too long!