Tropicals & Tender Perennials: What is the difference between an epiphyllum and a cereus?, 1 by Elphaba

Elphaba wrote:
I posted this in the wrong spot yesterday, so I'm trying again. Here's what I wrote:

I was at a nursery yesterday and they had an unidentified hanging plant that could be either a cereus or an epi. Today, I was at another nursery looking at what I was sure was a big epi and was told that it was a night blooming cereus. I bought it. Here's a pic, but how do you tell? If this is a cereus, it looks like my epis. I've seen some cereus that seemed more upright and even had spines. Is that right? Thanks for your help.