Below is an example of a product that is white and is on a plain white background. As you can see, this bottle has curves in it and you can distinguish it's general shape against the white background.
The trick here is to use the opposite of white reflectors (or card boards in my case) which is black. The whites tend to reflect the black into the camera and thus giving definition on the subject. Below is the setup for the above image.
Similarly, clear bottles with clear liquids are tricky ones as well. I had a hard time on the image below due to the fact that the bottle is glass that reflects almost anything. The angle of the shot made it a bit hard to do as it is also reflecting the dark glossy table.
Hope this helps when in comes to shooting things white on white.