One thing is not related to the other.
Freesync is just a way to handle variant refreshes without screen tearing. Those refreshes can happen faster or slower. If a refresh happens faster than the LCDs can make the transition (which is rare, and only will really be an issue on whole scene changes, and likely you'll never see ghosting anyway), it will still happen.
That said, Sync tech has to do with human perception of changes that respond more precisely, and eliminating stutter (which happens because the refresh can't occur at the cyclical vertical refresh, which is mostly an artifact of CRT tech anyway). It is frustrating that nvidia has pushed proprietary sync tech that is costly to implement, rather than go with "Free Sync" which only requires firmware changes for most basic monitor controllers.
It seems like AMD's real push here is to maintain Free Sync capability as monitor manufacturers increase the color gamut and enhance LCD response times.