Image means to reveal and likeness is to reflect
Here is how the difference works. A man comes across a pool of water in the road and he sees his likeness – it looks a little like him. But the water is actually dirty with rocks and silt, reflecting some of pure water but a whole lot more of what is fallen humanity.
This is a picture of fallen humanity. Fallen humans are easy to spot. We see them in prison photos and police mug shots. We may or may not see the image of God because there is so much dirt and silt.
What is difficult is seeing a fallen man, nicely dressed, educated and prosperous, and on the outside not looking fallen at all. We say ” Oh that person would never go to hell. He is so nice.” But we are not looking at the image of God in that person but only the likeness, vastly cleaned up.
All men have the spirit
All men have the spirit of God in them because He has created them in the image of God. We confuse the spruced-up, elegant man with the image of God, when really there are two natures there. Your life is about which one of these natures will eventually rule.
God’s purpose for us as redeemed people is to bear the image of Christ. We are to reveal what He is now in us in holiness.
I thought this especially valuable in helping to explain why missionaries can be so confused about foreigners. I met many wonderful people in China but they were un-redeemed. It would be easy to simply say they don’t need God because of the likeness of Christ in them, and ignore the whole package of salvation.
Our job is to bring forth the image