Should be nearly identical in terms of how you start it, fly it, etc. The BMS F-16 has been gone over by real F-16 pilots many, many times, and it's incredibly close within that non-classified window. If ED takes the same approach, which I assume they will, than the differences should end up minor. Probably in the avionics systems itself if ED has different or conflicting information for things like the radar and targetting systems. I fully expect it to have all the core master modes like MRM, NAV and DGFT. I expect all of the HOTAS controls to effectively be identical, since in BMS they are already based on the F-16 NATOPS.
There will be small things I'm sure, but anyone who knows how to fight the Viper in BMS will have a massive head start in the Viper in DCS.