Can I use baking powder instead of baking soda to whiten teeth?

Nope. Neither will really whiten your teeth. Baking soda is abrasive and may remove some surface stains, but it does not really whiten your teeth. Excessive use may actually wear your enamel away. Professionally dispensed products are the strongest and best way to whiten your teeth.
No. Baking soda doesn't really whiten teeth: it is a cleanser to remove debris and plaque from your teeth.
Both ineffective. Leave the baking ingredients in the kitchen. They really don't work very well. Waste of time and money. Best solution is have your Dentist professionally whiten your teeth, then use whitening strips or whitening toothpaste for maintenance. Also avoid heavily pigmented foods.
Teeth whitening. You can use baking powder instead of baking soda to remove stains only. OTC bleach and whitening tooth paste could be used as a supplement only. A professional teeth whitening without laser, followed by home whitening system with custom trays for the long term effect.