can you please explain the difference between a picture and an image?
Although both means the same, they have slight differences in the way they are used. Image usually refers to an image file in a computer (soft copy); or image is also referred to a "picture drawn by fancy".

Conceptually, picture is the right word if you are trying to refer to a photograph or a hard-copy of an image printed from a computer.

an image has a broad meaning, like humanbeing is God's image on earth or a son is an image of his father. You cannot say a humanbeing is a picture of God on earth or a son is a picture of his father. A picture can be a drawing or from a camera. A photo is produced from a camera.