Where's Rev when you need him? I always reference his Sunny D pictures; somewhere back in the archives there is a thread on the differences, see if I can dig it up.
That last pic is a good representation. The vivid's tend to be a darker more orangey orange instead of a yellow orange, and the Sunny-D's have a sparkly skirt, which the vivid's do not.
those are vivid rainbows
vivid rainbows have a black bat wing type of stripe in them that the sunny d's dont.here is a macro of my vivid rainbows.you can clearly see the bat design im talking about
well it seems half the people say sunny d and half say vivid rainbow, lol. with the side by side comparisions its it possible they are the same polyp morphed a little due to lighting? for example i used to have some armageddons, if they were highed in light they got more red and in lower in light got more black. same polyp but different amount of colors due to lighting.