A couple of questions from a new iphone owner

I'm new to apple and ios, and the iphone5 is my first apple device. I'm curious, is the usage statistics correct? (Settings > General > Usage > Time since last full charge) I recently got 7 hours with 7% remaining the other day and I am curious as to how this usage time is measured. I am very happy about it but somehow I still can't believe it.

Is the usage time here the same as screen on time in android?

Does the standby time include the usage time? Are they independent or does standby time include usage time?