Certainty - pertaining to probability.
Accuracy - is all about measurement.
As for the question of "Is it just semantics?," well.. no two words mean the same thing, and the same word may have different meanings depending upon the person who used it and when it was said, IMO.
I did not vote.
Ka Pilo,
I have always seen it this way:
Accuracy = closeness to the true dimension (bullseye)
Precision = variation in measurement (grouping)
Mind you I was influenced by the attached target graphic!
Top left is accurate and precise.
Bottom right is inaccurate and imprecise.
You get the idea...
Therefore,
certainty would have to be 100% accurate and 100% precise (an impossibility).
Truth in advertising means informing the customer of the degree of uncertainty they can expect. Continual improvement for a lab would include determining and removing the root causes of uncertainty.
John