Before revision: While the latter always fills the width with the web page, the former uses one of the five predefined fixed widths, depending on the size of the screen showing the page: Smaller than 576 pixels 576–768 pixels 768–992 pixels 992–1200 pixels Larger than 1200 pixels Once a container is in place, other Bootstrap layout components implement a CSS Flexbox layout through defining rows and columns.
After revision: While the latter always fills the width with the web page, the former uses one of the five predefined fixed widths, depending on the size of the screen showing the page: Smaller than 576 pixels 576–768 pixels 768–992 pixels 992–1200 pixels 1200-1400 pixels Larger than 1400 pixels Once a container is in place, other Bootstrap layout components implement a CSS Flexbox layout through defining rows and columns.