Large Grid
Space Engineers grids can be mobile Small Grids, mobile Large Grids, or (large) Stations.
Mobile Large Grids are typically ships used for interplanetary travel or for fighting against other large-grid ships. Other examples of Large Grids include wheeled mobile bases, atmospheric haulers, interplanetary explorers, mobile mining platforms, battleships, shuttles, motherships with hangars and docking platforms, and so on.
Mobile large grids are typically started by dropping a large 
Landing Gear and building on it.
Large grids are built out of large-grid blocks. Note that some functional and decorative blocks are only available in large-grid size and some are not available as large-grid blocks. Assign the block to the toolbar and press the number of the slot again to toggle between large and small size variant, if available. When attempting to add a new block to a large grid, the large-grid version is automatically selected. If a block does not have a large-grid version, you can’t add it.
Tip: Read the Rotor article to learn an advanced trick how to add small grid blocks to a large grid.
Comparison
- Being more durable than small-grid grids, large grids are powerful late-game craft in survival, since they are the only ships that can have on-board
Refineries, 
Assemblers, 
Jump Drives, 
Contract Blocks, 
Store blocks, and Upgrade Modules. - Large grids are more often designed to be multi-crew than small grids, but that’s not a requirement.
- Large Grids are made of Blocks 125 times larger than the volume of Small Grid blocks. This means you need 5x5x5 small cubes to fill one large cube. This does not, however, mean that the mass and costs are increased by 125 times, since large grids blocks are “hollow”, so to speak.
- The static variant of a large grid are stations (see there).