Grid
Grids come in handy when you have multiple items that you want to display side by side or when you want to display couple of items in a particular layout.
Usage
The two column grid divides the page into two equal halfs such that the elements are aligned side by side.
The three column grid divides the page into three equal halfs such that the elements are aligned side by side.
Masonry layout is a layout method where one axis uses a typical strict grid layout, most often columns, and the other a masonry layout. On the masonry axis, rather than sticking to a strict grid with gaps being left after shorter items, the items in the following row rise up to completely fill the gaps.