Whole:

The salmon is gutted and offered whole.
Fillet:

The sides of the salmon are separated from the ribs and backbone, producing two long portions of meat. A fillet of salmon may contain a single set of large bones, depending on the type of cut.
Portions:

A fillet is cut transversally into smaller portions.
Steaks:

The entire salmon (without the head or tail) is cut transversally through the backbone, producing portions of about one inch in thickness.

Salmon Mignon:

This is a boneless Steak. "Salmon Mignon" is two de-boned salmon fillets are held together with a mesh specially designed for cooking and then cut into steak-size portions.