I don't know that there are two distinct types. What I see are those and many versions in between. In either case, it involves an inflammation of the intestine and the fish will soon stop eating. Metronidazole or dimetronidazole always work as long as the directions are strictly followed. After 5 - 7 days of treatment, the fish won't resume eating immediately because it needs to heal. Feeding usually resumes 10 - 14 days after start of medication.
Good luck, Willie