The Scythe modular board adds a new level of variability to Scythe, with the map (double-sided board and 4 big double-sided tiles) and the faction locations (home base tiles) changing every time you play. The modular board adds a drafting element to setup, along with a variant for a tighter map at low player counts.
This is a completely new board designed specifically for the tiles (which are designed specifically for the new board). Both the board and the tiles are double-sided to maximize variability. When you play Scythe with the modular board, you will not play with any other version of the Scythe board.