by Martin Laws, Front End @ Ample Organics
Flexbox is one-dimensional. Each row becomes its own flex-container, meaning that members of a row only know about their direct siblings, they are not aware of members of other flex-containers. This is not a problem when the layout is one-dimensional (e.g. top -> bottom, left -> right), but becomes highly problematic when you want vertical and horizontal layout control.
Grid allows you to declare two-dimensional layouts, much in the same way as third-party grids (Bootstrap, Foundation, Skeleton, etc.), but is native to CSS.
