Yes, it can be a bit confusing. The complications are with the instrumentation used for the surveys. Some instruments are more "sensitive" than others. In other words, some can "see further" or have better depth penetration. If you look at typical "frequency domain" EM surveys, they are generally reported as "layers" which reflects different depths of penetration.

I am not a geophysicist. I leave it up to them to define the "anomalies" or conductors. As a geologist, it is generally the mag maps which I try to interpret and help formulate a geological map reflecting the various rock types present. Combining both generates drill targets.

geoprof