According to Amazon's product page, Destiny's extra content will be exclusive to PlayStation until at least fall 2015.
"Exclusive content for PlayStation 4 owners includes the Exodus Blue Competitive Multiplayer Map, Dust Palace Strike, Weapons, Ships and Gear that will only be on PlayStation until at least Fall 2015", the retailer states.
Destiny will be released in September 2014 for both Playstation and Xbox platforms (and Activision are also seriously considering porting it to PC too). The beta will kick off in July.