The CB550F has a lighter four-into-one exhaust, slightly flatter handlebars, and a different fuel tank without chrome trim. The CB550F is part of the Honda Super Sport range, along with the CB400F,  an CB750F.
The CB550F includes a lighter four-into-one exhaust system, handlebars that are slightly more upright, and a fuel tank without chrome trim. It belongs to the Honda Super Sport series, which also encompasses the CB400F and the CB750F.