One difference is that Lab data is useful for testing, Field Data is better for ranking. Lab data is about the performance data found in a unique environment. Chrome Dev Tools and webpagetest.org tools are commonly used to gain Lab Data. Field Data encompasses data collected from the collection of users that visit your site’s pages using the Chrome browser. Field Data is what populates your Google Search Console reports as well as Google Page Speed Insights (which relies on both Lab and Field data for its page reports).