Often people get confused in doing drawing with their imagination. This aspect is very different it has implications which you shall draw from using your brain.

Drawing from the memory usually means that you are trying to recollect some of the real images that have been captured using your brain in the past tense, and you are trying your best to draw or even paint them.

Drawing from your imagination is quite different, which actually means that your imagination has a certain image which will be completely like a fantasy, and you are trying to draw them out.

So looking at both the aspects you can see that one of them is a realistic image which you will draw and the other one is the very fictitious image. Learning to see the difference in these two types of the drawing should definitely be a very good beginning to clear the confusion which arises in your mind.

If you find some difficulty in drawing your fictitious image, which is in your mind, I must say that you will be lacking in the ability to express your drawing well which can be solved very easily. Just take out some time to improve your foundation in drawing so it will be easier for you to express with the pencil so that your problem can be solved.

Now just say that you wish to recollect an image, which is already captured in your mind but even then you are not able to complete it as you feel that you do not have that great skills for doing so. Then the problem might lie in your source image itself. Your mind has already skewed the image and somehow that information shall be transferred on the paper.

If you feel that both the things are not working then the last option is you should use your photographic memory where things will be easier for you.