Terms/names for our dead finny friends sold at grocery stores and elsewhere vary across the land and across time.
Names are also changes so as to reap more profit for the seller.
A name for a fish is just that, a name given by a human.
Some folks can identify fish by site/taste/etc. but even experts can be fooled, as evidenced by some news reports covering investigations into fish being sold under names other than the actual factual name of the fish.
Back in the 1960s in the east Frisco bay area I noticed that butterfish was the name given to various varieties of shark. You never saw shark sold as shark but the sellers did not try to hide the fact their butterfish actually was shark.
Tasty stuff, though some shark are not palatable and some can be harmful if not treated/cured/cooked properly.
As a top predator shark are also known to hold rather large amounts of mercury in their flesh. Gotta' be careful!!!
If curious, do a Web search. There's some interesting articles scattered about regarding the names given to fish and the ways consumers are ripped off.
Not suggesting those above were defrauded. Just reading the posts made me think of the large amount of fraud going on here and there regarding fish, selling fish, naming fish.... taking the suckers for the proverbial ride.
Carry on