You can buy it in retail starting from essen 2019. Thera are no difference instead of the 3d map and coins that are kickstarter exclusive.
As said above, there won't be a late pledge or pledge manager where backers can add more copies to their account.
The retail base and expansions will be the same and will be sold 6 months after the last copy arrived at backers houses. They will try hard to make that happen 6 months before Spiel 2019.
There was a special content KS exclusive box that included 1 KS exclusive base game tile (executive officer), an alternative 3D map with recessed spaces and metal coins.