The Lock setting determines how often you will need to unlock the LastPass app with biometrics/a pin code/your master password, and the Auto Logout setting determines how often the app will fully log out of your account and you will need to fully log in to the LastPass app again with your username and master password.
The answer is still ambiguous to me. What is the functional difference between having the app unlocked and the user being logged into their account?
I think what most users want is when they are actively using their device they will only need to enter their master password once and then when user interaction ceases for a duration passwords become unavailable. How to achieve this given the security settings is confusing. For example why does both the lock and logout sections have an idle timeout?
Using the lock app automatically option seems to require me to always reenter my master password on every password fill operation irrespective of the idle timeout setting (screen is not turned off during the interval).