Below is a graph comparing the difference in how many calories you will burn rebounding vs running. The graph is based on a person who weighs 160lb (which is the national average).
For a more detailed table comparison of rebounding vs running.
In addition to being more efficient that running, exercising on a rebounder is also much easier on your body. While jumping on a rebounder you experience 80% shock to the joints than running. This is especially important for anyone who has back or knee problems. It is not at all uncommon for people who are no longer able to run due to back pain to discover that they are able to exercise on a rebounder without experiencing any pain at all.