A walkthrough is typically led by the author of a document, for the purpose of educating the participants about the content so that everyone understands the same thing. A walkthrough may include "dry runs" of business scenarios to show how the system would handle certain specific situations. For technical documents, it is often a peer group technique.
Inspection
An Inspection is the most formal of the formal review techniques. There are strict entry and exit criteria to the Inspection process, it is led by a trained Leader or moderator (not the author), there are defined roles for searching for faults based on defined rules and checklists. Metrics are a required part of the process.