Difference Between Open Source and Freeware

What is the difference between open source and freeware?

Open source is free software which allows people to view the program's source code, modify, and redistribute it, while freeware is software that is available to the public at no cost, or sometimes for a optional donation, but are not allowed to change the code.

Photo Story & Google Sketch-Up & Pivot = Freeware
Scratch = Open Source