Build Solution and Rebuild Solution option in VS.Net

We have two options for compiling and creating builds for our application. Such as

1)Build Solution
2)Rebuild Solution

1)Build Solution
The Build Solution option compiles only particular project files and components in the solution that have changed since the last build.
For example: Assume that we have two projects P1 and P2 in our solution WebsiteSolution. When we compile the solution using Build Solution option after making some changes to P1 only Pj1 will be compiled and built but P2 will not be compiled.

2) Rebuild Solution
The Rebuild option builds all project files and components.
For example : Assume that we have two projects P1 and P2 in your solution WebsiteSolution. When you compile the solution using Rebuild Solution option after making some changes to P1, both P1 and P2 will be compiled and built even though there are no changes made to P2.