amandaonwriting:

Four Types of Book Editing

1. Developmental Editing

Any or all of the following:

• Working with the client and, usually, the author of a book or other document to develop a manuscript from initial concept, outline, or draft (or some combination of the three) through any number of subsequent drafts
• making suggestions about content, organization, and presentation, based on analysis of competing works, comments of expert reviewers, the client’s market analysis, and other appropriate references
• rewriting, writing, and researching, as needed, and sometimes suggesting topics or providing information about topics for consideration of authors and client.

2. Substantive Editing

Improving a manuscript in any or all of the following ways:

• identifying and solving problems of overall clarity or accuracy
• reorganizing paragraphs, sections, or chapters to improve the order in which the text is presented
• writing or rewriting segments of text to improve readability and flow of information
• revising any or all aspects of the text to improve its presentation
• consulting with others about issues of concern
• incorporating responses to queries and suggestions creating a new draft of the document

3. Copy Editing (sometimes called line editing).

Any or all of the following:

• correcting spelling, grammar, punctuation, syntax, and word usage while preserving the meaning and voice of the original text
• checking for or imposing a consistent style and format
• preparing a style sheet that documents style and format
• reading for overall clarity and sense on behalf of the prospective audience
• querying the appropriate party about apparent errors or inconsistencies
• noting permissions needed to publish copyrighted material 
• preparing a manuscript for the next stage of the publication process
• cross-checking references, art, figures, tables, equations, and other features for consistency with their mentions in the text

4. Proofreading. Comparing the latest stage of text with the preceding stage, marking discrepancies in text, and, when appropriate, checking for problems in page makeup, layout, color separation, or type.

Proofreading may also include one or more of the following:

• checking proof against typesetting specifications
• querying or correcting errors or inconsistencies that may have escaped an editor or writer
• reading for typographical errors or for sense without reading against copy

Definitions from Freelance Editorial Association

From Writers Write