Is there any difference on power charger between iPhone 6 vs 6s?
I'm worried that there is a difference and that I'll have issues when I use the iPhone 6 charger for iPhone 6s
It looks similar but can I get it confirmed?
Both use Lightning cable, so we are good there. Regarding power, the 12W charger is compatible with all iPhones. See product Compatibility section of 12W charger.
iPhone iPhone 3G iPhone 3Gs iPhone 4 iPhone 4s iPhone 5 iPhone 5c iPhone 5s iPhone 6 iPhone 6 Plus iPhone 6s iPhone 6s Plus
So you should be confident of charging iPhone 6 or 6s with up to 12W charger. The higher the wattage the lesser is the charging time.
You can use iPhone 6 charger for iPhone 6s and vice versa. You can even use your usb port on your Mac/PC to charge them both (however the charging might take a little more time than). There is no issue about that.
Yes it's safe to use iPhone 6 charger to iPhone 6s. As what the guys said, they have the same port and supports 12w charger so there should be no problem.