What’s the difference?

What kind of tool is required for code review? What are we trying to accomplish? How much of the code must be reviewed at a time, and why? These are some of the questions that we get caught up in, that prevent us from deploying effective code review in a development organization. One way to cut through the arguments and move forward is to realize that there are different types of code review, with different goals. Here are some parameters of two major, but different types:

Code Review type 1

Key question: Does this change accomplish what it was supposed to, while doing no damage?
Desired code author response to comments: Revise changes
Under review: changed files with diff
Tool: diff comparer
Required feature as a code review tool: right-click submit comment
Nice-to-have features (but could be in a separate app): right-click definitions

Code Review type 2

Key Question: Is this code designed well, so that it is easy to fix and extend?
Desired code author response to comments: Refactoring / renaming
Under review: any subset of entire codebase, starting from a given area of the code
Tool: source code browser
Required feature as a code review tool: right-click submit comment
Nice-to-have features (but could be in a separate app): code editing