LG uses 2 different methods to control the compressor speed. One is to vary the voltage, the other is to vary the frequency.
They are 2 different systems, different controllers etc. and components are not interchangeable. LG lables both types "linear compressor".
Look on the compressor label. If it says something like 0-220v 60hz its variable voltage. (Voltage can be 0-180 or anything really)
If it says 200v 0-60khz its variable frequency.
Variable speed compressors will only have continuity between 2 of the 3 pins, the 3rd pin isnt connected to anything.
Variable frequency compressors should read identical resistance between any 2 pins.
Hope this helps.