PageSpeed, not be confused with “page speed”, is defined as the composite score provided by Google’s PageSpeed Insights tool, calculated by assigning a numerical value to a set list of “Best Practices” designed to both deliver and render a web page as quickly as possible across any device at any Internet speed.

While similar, these are starkly separate terms, there are notable differences between the two as they are used in context & literal application.

Google’s PageSpeed Insights was designed to report on the real-world performance of a web page for mobile and desktop devices, providing suggestions on how that page may be improved by showing the recommended list of best practices for site speed optimization, such as everyone’s favorite:

“Eliminate render-blocking JavaScript and CSS in above-the-fold content”