I'm not sure 100%, but you can get all sorts of options and combinations on any trim package. But the platinum is a specific color and maybe has a bell or 2 that are only available on it.
When we got our 08 Expedition EL, it is listed as a Eddie Bauer package. So it has dual tone paint, 2 tone leather, and the EB standard stuff. Ours also has sunroof, heated/cooled seats, navigation, 20" wheels, 2nd row captain's chairs, and DVD entertainment system. Which a lot of that stuff is standard on the Limited. The only options that a Limited has that ours does not is the electronic side steps and heated 2nd row seats. But the Limited was only offered in a white exterior and black interior, or a black on black scheme. So ours is a very loaded EB.
I'm sure it's similar when the Platinum came out. The King Ranch is also very nice, obviously having the unique interior, but they are well loaded. My wife's friend has a KR F150 that I drove once and it has all the bells and whistles too, not sure if it has EVERYTHING possible, but I'd have no issue driving it. The Platinum trucks I've seen are silver and black IIRC, not sure about F250/350, I think they have Platinums available too. Probably an easy search to figure out.