Grid lines are the horizontal and vertical lines that appear on the slide as a guide for placing and aligning objects.

Grid lines can help you create a balanced and symmetrical layout for your presentation.

To show or hide the grid lines, go to the view tab and check or uncheck the grid lines box in the show group.

You can also adjust the spacing and snapping options for the grid lines by clicking on the grid lines options button next to the checkbox.

Guidelines are the dash lines that appear on the slide when you move or resize an object.

Guidelines can help you align objects with each other or with the slide edges.

To show or hide the guidelines, go to the view tab and check or uncheck the guides box in the show group.

You can also add, remove, or move the guidelines by right clicking on the slide and selecting grid and guides from the menu.

Guidelines are different from grid lines, which are equally spaced across the whole slide.

Smart guides are lines that appear on the slide when you drag, rotate, or resize an object.

Smart guides can help you snap objects to other objects or to specific angles or positions on the slide.

You can also turn on or off the smart guides by pressing the alt key while moving or resizing an object.

Smart guides are different from guidelines which are user-defined and can be moved or deleted.