There are many ways how you can simulate one with the other, _if_ you are willing to instrument your images, e.g. through ssh. If the image is not instrumented, your whole API call falls flat on its face.
Deltacloud is a general-purpose cloud API, and as such can't assume that images are instrumented in any particular way. The situation is very different with jclouds which can make all kinds of assumptions about what's in the image.
What can i do with new vm's in a cloud without discover them and get more configuration to the vm. If we install a new system from a template we need to do always some steps like install something else to bring up services or put puppet there to bring up services later. With one injection like firstboot or postcommand, everything is possible then. Put, for example "firstboot" has always a dependencies to a guest operating system, in which style firstboot is running. On the other hand, the most cloud providers have the "same/a" range of supported operating systems.
Thomas