GeckoView what is the difference between geckoview progressDelegate.onPageStart vs navigationDelegate.onLocationChange?

Question

Both have the same description "A view has started loading content from the network."

When to use which one? Does one of them load earlier or do they get triggered at the same time?

navigationDelegate: https://mozilla.github.io/geckoview/javadoc/mozilla-central/org/mozilla/geckoview/GeckoSession.NavigationDelegate.html#onLocationChange(org.mozilla.geckoview.GeckoSession,java.lang.String,java.util.List)

progressDelegate https://mozilla.github.io/geckoview/javadoc/mozilla-central/org/mozilla/geckoview/GeckoSession.ProgressDelegate.html#onPageStart(org.mozilla.geckoview.GeckoSession,java.lang.String)

I can't find any example and the documentation is very basic, it doesn't state when to use method in progressDelegate or navigationDelegate.