Just a silly comparison ...
If pharmacies use toilet tissue-X, that must mean that Toilet tissue-X is pharmaceutical grade.
What I'm getting at is that there may or may not be any difference. If pharmacies use a product, it may be driven by cost, ease of attainability, contract, etc...
The US military gets contracts based on the lowest bidder, and senatorial handshakes. This does not strictly guarantee the highest quality product, but marketing often implies it (military grade).
Have you ever walked into a doctor's offfice and not seen adverts for some drug or another? Where is the guarantee that it is any different in a pharmacy. It seems unlikely that you would pay for fish oil and get canola oil instead, but this is one of the risks we take with supplements, which are not strictly required to bottle what is advertised.
LSS, if you think its fish oil, it probably is, and there is not likely any difference between two brands of oil. It seems a trivial substance over which to make that kind of claim. But if he didn't, does he stand to lose revenue? It is a confounding bias.