Space is “defined when something is placed in it”, according to Alex White in his book, The Elements of Graphic Design. Incorporating space into a design helps reduce noise, increase readability, and/or create illusion. White space is an important part of your layout strategy.
Hierarchy shows the difference in significance between items. Designers often create hierarchies through different font sizes, colors, and placement on the page. Usually, items at the top are perceived as most important.