launchctl list shows bundle identifiers of running application, there is a number after that what is it?

Question

command and its output

launchctl list  | grep Terminal

94502   0   com.apple.Terminal.2000

What is the 2000 number referring to? 94502 is Pid and 0 is exit status

What does it mean if pid is empty _.

_   0   com.apple.Terminal.2000

What is the difference between this and LaunchAgent/LaunchDaemonservices