Which is better: the optic white toothpaste or mouthwash?

About the same: Both will work to a degree. The longer they are in contact with the teeth, the better the whitening. Crest white strips work better and even better is custom trays with bleach or in office bleaching like zoom or boost!

For what?: In my opinion neither (nor most other similar products) do very much. What are you trying to accomplish? Ask your own dentist what he\she recommends and why? Mouthwashes are generally not necessary and there are more effective ways to whiten teeth.

Tooth Whitening: Actually, colgate offers a "kit" of bleaching products by optic white. They include a tooth paste and a rinse. My opinion is that in combination, this is a "good" plan; however, keep in mind that these are both "over-the-counter" products and their efficacy is at a "safe" level because of this classification. A dentist prescribed product or "in-office" procedure would be more effective.