http://www.theverge.com/a/apple-iphone-7-review-vs-iphone-7-plus
Right now, what this means is that you can switch to a true 2x zoom by tapping on a button, which is very nice. You can also digitally zoom the 1x lens to 2x, where the telephoto takes over, and then digitally zoom the 2x lens to 10x. Digital zoom is still digital zoom; anything past 4x definitely looks like what you’d expect from grainy digital zoom.