On section.io Real User Monitoring just wondering, what's the difference between page load time and page load breakdown?

Page load time will show the median, mean and 95th percentile of total page load times from users. Page load breakdown will show you what made up the Page Load time. Specifically it will show you how much of the page load time is spent on the backend(getting the HTML document) and how much in the front end (loading all the other assets)