Is renderStart in summary_pages table same as FCP.? Appears FCP is derived from _chromeUserTiming.firstContentfulPaint from the CrUX dataset (field data) whereas renderStart is from lab measurements; conceptually they appear similar. Requesting help in understanding the difference between the two metric.
The definitions are as follows:
a) The Start Render time is measured as the time from the start of the initial navigation until the first non-white content is painted to the browser display (https://sites.google.com/a/webpagetest.org/docs/using-webpagetest/metrics)
b) First Contentful Paint (FCP) measures the time from navigation to the time when the browser renders the first bit of content from the DOM. (https://developers.google.com/web/tools/lighthouse/audits/first-contentful-paint?utm_source=lighthouse&utm_medium=unknown)