At one time home blood glucose test meters measured glucose levels from a FULL or WHOLE blood sample and confusion reigned as it still does to some extent.
My home B/G meter has a setting that approximate any reading to either a FULL blood or WHOLE blood sample as well as what it calculates as being a PLASMA equivalent of having a proper Blood test done in the LAB where the blood sample is separated into the Haematocrit and Plasma compounds by them spinning the sample in a centrifuge before analysis. This is not to be confused with the HbA1c or Frutosime test readings which are both something completely different and indicate average Blood Glucose levels over a set time period of several weeks .
Modern Home Blood Glucose testing meters, though they still obviously use the FULL or WHOLE blood sample blood from the finger prick, use a different technology to indicate the final result, measuring the conduction that occurs over two electrodes within the test strip. Yet again the result is computed and is therefore something of a compromise.
Ultimately the truly only accurate way is to have the blood sample tested at the Laboratory, but even with the limitation on most home B/G meters reasonably accurate results that are comparable can still be obtained.