What would you to make your teeth white if receding gums and eroding enamel?

Sounds like... ...Your dentist will first need to make sure you keep your teeth intact before worrying about their color.
Little difference. Actually the same thing that would make your teeth white without the receding gums & eroding enamel. However, having that done is more problematic & more likely to cause tooth sensitivity and tingling of the gums. I would suggest that you have a consult with a dentist to discuss how best to keep your teeth & gums healthy both now & in the future & when and how tooth whitening would come into play.
Whiten teeth. Definitely use a professional whitening system in a dental office, they have the ability to block and protect your gums and teeth for sensitivity and recession.