Tushar,
Let's first of all be clear and say that the difference between these two words is unimportant for the PMP Exam. I used them in the examples to explain what you might need in a project. And as you have already said: I see materials more like "raw materials" and goods more like "finished items". And on any given project it is possible that you may need both: In one task you need raw materials (i.e. concrete powder and water) to work with and on another task you may need a finished good (i.e. a ceiling lamp) that needs to be installed.