While you might often think of contrast in design as having to do with the physical characteristics of a particular design element (like its size, weight, color, typeface, and so forth), by definition “contrast” is broader than that—you can also create contrast by making something different in position or location.
When several things on a page look identical or very similar, creating one object on the page that is different will draw attention to it. Likewise, if you have several visual elements in a design that are all in one general location, placing something far away from the rest creates contrast in space.
Creating contrast through space and position is especially useful if you want your audience to draw their attention to one thing, muting or masking the other elements on the page. Creating contrast by space or position doesn’t make the other design elements irrelevant (if something is irrelevant, it shouldn’t be in the design), but the contrast does make a particularly strong emphasis on the one thing that is different.
Use contrast by space or position if you want something in a crowd or a group to stand out from something else. You might, for example, want to emphasize how one product stands out from many others or how one piece of data is different than all the rest. Consider how you might use space and position to draw direct contrast and comparison of one from the group.