Functionally, there's no difference. FreeSync, is FreeSync.
BUT, with an HDMI out from the XBOne to HDMI on the monitor (or an HDMI to DP passive adapter), you'll either achieve 4K @ 60Hz without Freesync (if the XBO is HDMI2.0) or 4K @ 30Hz (if it's 1.4).
SO whats the actual difference between freesync over hdmi and freesync over displayport ? does that mean ill get 4k@30hz with freesync over displayport
Functionally, there's no difference. FreeSync, is FreeSync.
BUT, with an HDMI out from the XBOne to HDMI on the monitor (or an HDMI to DP passive adapter), you'll either achieve 4K @ 60Hz without Freesync (if the XBO is HDMI2.0) or 4K @ 30Hz (if it's 1.4).