Inland fisheries are done in lake orrivers
marine fisheries are done in oceans
There are different concepts that makes them different from each other.
Freshwater have different needs such as they need a lower salinity and lower pH. Also, they don't need to take out salt out of their system but saltwaters does need to because they have a different organ for saltwater environments.
Saltwater also originate from larger bodies of water than freshwater species. Most saltwater species (I think) don't school as most freshwater fish we keep.
There are so much things that differ each other.