Chrome Developer tools Performance timing mismatch

I tried verifying the load time of a webpage via developer tools in chrome. I was able to find it through ‘Load time’ displayed at bottom of Network tab(option 1).

However I came to know about performance.timing javascript api(option 2) which could also fetch the total page load time in milliseconds using below formula

pageLoadTime= performance.timing.loadEventEnd – performance.timing.navigationStart;

I could see a mismatch in the duration provided by Option 1 & Option 2

Does anyone know why this mismatch occurs?
Also which one should I consider for finding the total page load time