I have seen a lot of different forms of columnaris, it's very variable. It often causes 'receding white line' finrot. The mouth lesions are most commonly seen, along with the body patches. Another typical form is 'saddleback' where you get the white patch usually with red edges that spread from in front of the dorsal fin. There was a post in the betta section recently showing the worst case I have ever seen, half the betta's back involved and several mm of flesh eaten away, but he had it for weeks. I've seen strains that kill in under 18 hours and strains that take days or weeks. Fast acting strains are usually obviously dying by the time you notice anything wrong at all. Slow acting strains will be cured by maracyn. Usually a combination of 1 and 2 is recommended. If maracyn 1 doesn't work most other antibiotics will (kanamycin/streptomycin/erythromycin family, tetracycline/oxytet, chloramphenicol)
Ich looks like the fish has been sprinkled with salt and causes flicking and rubbing. Fish with columnaris don't scratch, they look uncomfortable and very sick, refuse food, hang at the surface or rest at the bottom, clamp fins and are lethargic.