Make everything that CAN be alike as alike as possible. Let the differences between stuff jump out as accents.
Mike Monteiro talking about simplifying a user interface so the differences in your content stand out, rather than trying to make every element look different.
Making every element look different inherently makes it more difficult to discover new content since you destroy easy to scan visual patterns. That, and you inevitably decrease the density of your content, which makes it more work for you to gather the information you need or want.