I'll chime in on this one.
If you purchased the season pass on either console, it is cross platform so you can download all the DLC maps and play them on both consoles. I do this with me and my nephew, who has the PS3 version of Ghost.
If you purchase the map pack by itself, you can only play it on the console that you purchased it on. If you purchase it on PS4, it won't show up on your PS3 and vice versa.