In my simple thinking, I thought of them as the same thing, but Adam Clark Commentary had a thought that caught me.
A thief is cunning and does it secretly.
A robber is aggressive and not afraid to do so publicly even if it turns to violence.
Now imagine a leader that does not care about the people. It is harder to discern the thief because they do their work in secret. It is hidden so you don't know who or how they are hurting the flock. They are more manipulative in order to get their gain.
A thief can turn robber when pressed, but usually the thief prefers the thrill of secret manipulations than outward aggressions. Maybe they like the appearance of being good.
While the robber just wants what they want and will do whatever it takes. They love the thrill of adrenaline and getting away with it. They don't care what you think.
No wonder sheep run.
No wonder it is important we know the Good Shepherd. He gives life and He gives it abundantly. He sacrifices for His sheep. He provides good pasture and gives freedom to move about. He knows you by name and calls you by name. You know He is trustworthy in meeting your needs and giving you more than you would ask for. There are no secrets and no violence. He cares.
What kind of shepherd are you following? Remember, shepherds represent leaders. Consider all areas of your life.
Here is the deal. We cannot know the Good Shepherd if we do not spend time with Him to know His voice and know His character. Once you know, you know. You do not want to follow those that want to steal, kill, or destroy.
How do you spend time with the Good Shepherd? Well, reading the book of John is a great place to start. Personally, as a woman I love the book of Luke because it has women stories. This is why theologians refer to it as the Women's Gospel. You might consider reading the Psalms and Proverbs. When I am hurting or in grief I read the Psalms so I can know how to talk to God. When I am struggling with people I read Proverbs so I can better understand how to interact with humans. The point is that the Bible helps you to know the character of God. When you know and understand His character you will recognize His voice and when it is a thief or a robber.
We must always ask ourselves questions, too. What kind of shepherd am I? Do I draw people to the Good Shepherd or am I doing it for me?
Kind of convicting!