Each version of the game has unique bonuses. But, everyone who pre-orders the game, regardless of which version, will gain access to the iron-grey Ardennes War Horse (a pre-order bonus from the original game) and the Outlaw Survival Kit. The latter are in-game consumables to replenish health, Dead Eye (slow-motion targeting) and other bits, according to a blog post from Rockstar. More than that, if you opt for a digital pre-order, you'll get between $500,000 and $2,000,000 deposited in your GTA Online bank account, depending on which edition (standard, special, ultimate) you pre-purchase.
RDR 2's $79.99 special edition has a handful of in-game bonuses including a reverse-dappled black-coated horse, power-ups for damage and awareness, a new outfit and early access to a handful of weapons, like the returning Volcanic Pistol. On the physical side, you'll get the unrippable map from the Collector's Box.
The ultimate edition features all of the special edition's story mode add-ons, plus the following bits for online play: a horse of a different color (a black chestnut racehorse) with a saddle to match, a customizable camp theme, weapons and a quick jump to online rank 25. Oh, and you'll get a steelbook case and the treasure map from the other versions, all for $99.99.
The $99.99 Collector's Box has all manner of physical accoutrement to round out your Dead West cosplay, including a locking cash box (a throwback to the GTA IV collector's edition), a coin, deck of playing cards, jigsaw puzzle, pin set, bandana and a map made of "unrippable" paper. Oh, and it'll also include a 150-page reproduction of the in-game merchant's supply catalog in addition to a dozen collectable trading cards found in the game.
What it doesn't include is a copy of the game itself, either physical or digital. Electronic Arts (and a few others) have tried this before, offering an expensive boxed set separately from the game disc. Earlier this year, you could find the Battlefield 1 set on Woot for a pittance of its original price.
Pre-orders are up on the Rockstar Warehouse and console digital stores, but if you're looking for a discount, Amazon's product page isn't live with pricing info. For its part, Rockstar said that the Collector's Box ships without the game "to ensure players can pair the Collector's Box with the game edition of their choice (physical or digital)."
Update: This post has been updated to reflect pricing information.