The concept of the ghost ball both in practice and in play will help you conceptualize the difference between the aim and collision points. The ghost ball is an imaginary cue ball that you visualize in your mind to help you make your shot. Imagining the ghost ball will give you the ability to see where the cue ball will contact the object ball. It will also help to visualize an imaginary line between the cue ball and object ball to see where the object ball will travel after contact with the cue ball.
You should visualize the imaginary lines first. Draw the line from the intended pocket through the center of the object ball. The point where the line comes out on the side of the ball farthest from the pocket is your collision point. Now visualize an imaginary cue ball at the collision point with the object ball. Hold that thought. Focus on that ghost ball because you now have to find the aiming point on the cue ball.
Setting up a ghost ball will help you envision where you need to strike an object ball in order to make a pocket.
Now continue the imaginary line that starts at the pocket and runs through the object ball. You want to visualize that same line running straight through the ghost ball. Visualize the line cutting through the center of the ghost ball. Where the line meets the center of the ball is where you want to point your cue stick when you position it behind the real cue ball. You may be surprised to see that the aiming point isn't even in line with the object ball; it may be off to the side.
If it's too hard for you to visualize the ghost ball at first, try using a real ball when you practice. Once you have your lines drawn (don't actually draw these, you could damage the surface of your table), place a real cue ball at the contact point. Find the center of the ball and observe it for a minute or two. Try this from all different angles on the table. Then take the real cue ball away and try to imagine it there instead. Eventually you should have a firm grasp of the ghost ball. It will definitely help your game.
There are several great pool video games that actually display the imaginary lines to help you pocket the virtual balls. Playing some of these games will assist you in understanding the concept of imaginary lines on the real pool table.
Once you have the ghost ball theory in place, finding your aim will be a breeze. Before you know it, you won't have to focus as hard. You'll be able to feel it out and find your aim very quickly. You won't even think about where the contact point is anymore, because finding the aiming point will be enough to hit the object ball and hopefully land it in a pocket.