What is the difference between salmon and mackerel?

Answer 1

Besides the outward physical differences, Salmon are known to spawn in fresh water and some species live their entire lives in saltwater until spawning season.

Mackerels are more closely related to what we call "Tuna." They range in size from the extra large "King Mackerel" to the much smaller "Spanish Mackerel." They do not live in fresh water.

Lastly, typically, Salmon meat is pink/orange due to their diet. Mackerel meat, typically is "white" or "clear," which is typical look to fish meat.

Pink/orange fish meat does not mean that it is Salmon. There are some trout farms feeding certain nutrients their fish making the trout meat look pink/orange.

Answer 2

Both are members of the same family, but salmon spend more time in saltwater, where few trout do at all. The main exception is the steelhead, which is a sea run rainbow trout.