According to the Thad Howard book, C. procerum (the large red-leaved species) and C. x augustum (of which "Queen Emma" is a variety), are somewhat similar. C. x augustum is a hybrid of procerum with C. zeylanicum and is supposedly larger than both parents, if that helps. C. x amabile is another cross with similar parentage. This one is said to have erect leaves while augustum's tend to spread, but that's the only distinguishing factor cited. The hybrids are also supposed to be sterile, but mine have set seed which has subsequently germinated, so either they're mislabeled or the info is not accurate. Nomenclature in this group of crinums seems to be a tangled mess, and there's not a good way to know for sure, unfortunately. Sorry this isn't much help - would love to know more myself, but I think I've exhausted all sources of info at this point.