Here’s all you need to know
Full spectrum contains additional minor cannabinoids found in the hemp plant to include trace amounts of THC. Isolate is pure CBD without additional minor cannabinoids. Isolate is best for people that are subjected to urinalysis tests for their profession. Full Spectrum is best everyone else.
Yes, REST contains CBN which can cause a false positive for THC. Also, anything in Full Spectrum form has the potential to cause a positive result for THC since it contains trace amounts of the compound.