When I tested Saturn vs Apollo in a local shop here, using a complete Rega set up amp and speakers, I could hear that Saturn gave a more crisp and detailed sound. Bass was much more abundant than the Apollo. However, when hooked up to my MF amps and EPOS speakers, I could not hear much difference between them. Didnt plunge into Apollo immediately. Settled with a Marantz + MF X-DAC combo first. Only a year later when the price dropped for Apollo here in Malaysia, that I purchased the unit. Now, I am running the the APollo directly hooked up to the amp, no longer via MF X-DAC.
So, to answer the thread question, I guess it depends on which system you are comparing the Apollo and Saturn with. With my set up, not much different. But with the Rega set up, there was a significant difference.