While blocks can be used in a variety of patterns, block patterns can take you further in the experience of creating pages and layouts.
Using block patterns, you can lay out and structure your site’s headers, content sections, and footers.
They allow you to quickly create and prototype your vision, says Tammie Lister in Block patterns are better than blocks.
Block patterns make it easier to to create what you want, without getting confused over what combinations of blocks to build.
Using a ready-made pattern provides a default style for your theme, allowing you to edit and style it as you wish.
I liked Lister’s analogy to a house,
It’s the difference between making a house brick by brick or a prefabricated one.