Substantive editing (sometimes called structural or content editing) aims to ensure that the structure, content, language, style and presentation of the document are suitable for its intended purpose and readership. This means that I will be looking out for half-formed thoughts that aren't quite convincing yet, paragraphs or sentences that could be rearranged that will make your prose pop and truly excite your readers, I will point out potential other directions you may consider taking your article or book that you may not have considered but will amp up the excitement and get readers responding to your call-to-action.
Copy editing aims to achieve accuracy, clarity and consistency in a document, so I'll be making sure you don't contradict yourself within the document (the workshop's on April 3rd, not 30th, right?) or accidentally make a claim that you can't follow through on. It does not involve significant rewriting, providing a single authorial voice, or tailoring text to a specific audience—these belong to a substantive edit.
Line Editing (PROOF READING)
Line editing, often called proof reading, involves checking that the document is ready to be published. It includes making sure that all elements of the document are included and in the proper order, all amendments have been inserted, the house or other set style has been followed, and all spelling or punctuation errors have been deleted. By the end of this step, your document is ready to go.