both don't use the same pins.
however, if you have the PiScreen sitting on top of the 40 pin header, you will not be able to easily access the other pins needed for the BerryGPS-IMU
If the PiScreen is sitting on the top of a Pi Zero, there will be some male pins on the PiScreen which are unused. You can see this in the red square below, I have highlighted what pins you can access to get the IMU working.
To access the Pi serial pins used by the GPS, you would need to solder some connectors to the bottom of the female header, highlighted in the yellow circle below. (the RX & TX pins are on the other side)
Mark --OzzMaker.com --