Is there any chance of being able to identify my NOID epiphyllums?
Color is the first thing to look at. What are other identifying traits that I should be aware of?

Size and shape of the bloom, and growth habit of the plant are the most obvious. That being said there are lots of look alikes out there.

I've heard several schools of thought on this. I have many that used to have tags, but have now become noids. I have found that I have many that look so similar, it is nearly impossible for me to put names on those that have lost their tags. In my garden, they become the orphans. I love them anyway but don't try to re-name them.

I'm with Linda! Half of mine are NOIDs and I wouldn't even try to name them. I think any one that tinkers with crosses gives them a name, but they don't register them. If you are wanting to put them in the data base, you should just call them Epiphyllums.