Mostly pattern, and the balance between the colors. In an older swirl, there's usually a clear argument for which color is the base glass and which is the ribbon. That distinction frequently gets lost in Jabos.
Another thing is how many colors you're picking up in your photos. The more shades, the more likely you're looking at a Jabo.
This one for instance. It actually has a relatively distinct white "ribbon" in the left view, but look at all those shades in the right view.