No one knows yet, the subject is one of intense debate. Farmed salmon are kept in cages at sea. Because they are crowded and valuable they can be given antibiotics to fight disease, traces of which could remain. Some farms feed them food made from ordinary grains and oils which makes them less rich in healthy oils. Others are fed more natural fish meal and have normally healthy oils.
Salmon farms are apparently having a drastically negative effect on wild salmon. On the other hand, it reduces the fishing pressure on the wild salmon; if it were not for the salmon farms the pressure to overfish might have been just as bad. Fish farming at sea is almost certainly necessary, but it needs much better regulation and improved techniques.

Very simple, hun: Farm raised fish are basically SAFER cos the controlled feeding process. Wild - "off shore" or "ocean raised" - fish are more likely to be contaminated by god knos wot - and have high mercury content. Its gets tricker w wild Salmon cos they apparently have higher nutritional value.

Farm raised fish are fed and cared for like cattle in a feed lot. They are fed on pure grains and other foods of the same quality as is fed to humans. These feeds do however contain fillers. - Like baloney - it is better not to ask. and I am not going into that.

All meat crops are fed similar fillers, so If this bothers you you can't eat any farm raised meat.

The food manufacturing process for farm animals is not controlled like the processing of people food. (If you have been watching the news lately, I am not sure that makes much difference.)

The fish are carefully medicated so they will not get sick. They are kept in carefully prepared and maintained ponds. In most cases the ponds are refilled with fresh water for each generation.

The main difference is that they have less flavor than "wild" fish. Most people consider this a plus. Most people don't like the flavor of "fishy fish".

They also have very low mercury content but they contain higher levels of PCBs.

My preference is for PCBs over mercury. You will need to make up you own mind on this issue.

By the way, If you prefer wild salmon, enjoy them quickly because before long there will be none left.

Make no mistake, an acre pond full of salmon takes a very large investment in both time and money and labor. If even one of them gets sick it could kill the entire pond.

These animals receive better care than most human children. ( As do the cattle and other farm animals. ) The only place humans have an advantage is that they do not have to worry about being eaten.

The quality. Farm raised are more pron to getting parisites, plus farm raised don't actually have pink flesh that's dye. The wild salmon get that colour from what the eat.