Walkthrough is a common term used during the informal meeting. In every project many walkthrough will happen to discuss about Business requirements, BCP plan, project evaluation along with managers etc. No pre-preparation is needed for this kind of meeting.
Inspection is a formal meeting which is a pre-planned activity. The appointment is generated for this meeting.
The Inspection may happen any time during the project phase. This may include the developers, testers, managers and even the client. The inspection is documented and circulated among the team members.
Review provides a powerful way to improve the quality and productivity of software development to recognize and fix their own defects early in the software development process.