What happens if I charge my iPhone 6 Plus with a Samsung Galaxy S6 fast charger?

I've been using my 6 Plus for over 11 months and it has been great living with it but I can't ignore the fact that it has an awesome battery life. All day is no problem for me with it, but the problem is that it is slow. Yes I've been using techniques such as turn on airplane mode, turn off WiFi and Bluetooth, close out all of your apps, log out of your social media if there are any, and use and iPad charger but this is not quite big of a difference. Samsung's new Galaxy S6 and S6 Edge have both fast chargers which I heard was very effective and good to have. I have neither a Galaxy S6, S6 Edge or even a note 4 or ever plan to buy one. But I wonder what would happen if I use that wall charger for my 6 Plus. What would happen?
Added (1). and by slow I mean slow charging, sorry

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