Hi,
Your right!
Looking closer at the script the CPU/GPU temperature are from the same sensor accessing; '
/opt/vc/bin/vcgencmd measure_temp'
& '/sys
/class
/thermal
/thermal_zone0
/temp'. No differences. Author may be seeing the differences due to the delay(propagation) accessing the same sensor thus different output for the same sensor.
Script will still produce the Temperature for the Rpi just be aware that the GPU & CPU temperature are from the same sensor since the SoC is on the same silicon.
Just edit out the GPU part of the script.
Sorry for miscue.
Hope this helps.
Have fun & enjoy!