vietnamensis looks like the polyps are in rows between ridges. This has more randomly distributed polyps, from my point of view.
I am both glad and sorry I don't have skeleton to use for identifying it! It did die back for a while but quickly grew over the dead part. Should have examined it when it died back. Might be impossible to ID this from a photo, really. I am going to stick with confusa because that is what it was sold as and I see enough evidence to switch the ID to vietnamensis. Both are very nice though.
Kate