Editing
In this instance, my role as your editor is to maintain the copy as you wrote it. But I improve it by applying what I call invisible mending, preserving the original text but improving the readability, syntax, style and organization. In this instance, I edit for clarity and accuracy, not so much for style. I remove the typos, goofs, errors and punctuation problems. Also, I clean up confusing phrasing.
Proofreading
This is exactly as it sounds. I act as your proofreader, and nothing more. In this instance, my role is to make sure your content is clean — free of typos, gaffes or punctuation snafus. I improve your work by doing some invisible mending.