If this is anything like the original game, it means that PS4 players will get access to Strikes and gear that won't be available to Xbox One players (and, perhaps, PC players?) until a later date. In practice, this means that certain content is gated off from the entire player base, because those PS4 exclusive Strikes are never Nightfall Strikes and vendors like Xur never sell PS4 exclusive items.
Meanwhile, non-PS4 gamers are walled off from the content entirely, and with each new DLC find themselves more and more in the dust for no good reason other than a financial deal between Activision and Sony. It's silly and it sucks...
...So it's deeply disappointing to see that this farce continues with Destiny 2. This was a good opportunity for the series to ditch exclusivity deals and focus on making the best game experience possible for players on whatever platform. What a shame.