I jump back and forth between operating systems quite a bit, but after using Android as my phone operating system of choice for years, there are just a few things that are glaringly different while using iOS. Here they are, my favorite timesaving usability enhancements from Google.
Different keyboards
Exceptional text prediction, swipe to type, and amazingly accurate speech to text. You can move back and forth between these options at will instead of just being constrained to the one keyboard of iOS. 
Controls from notification shade
Just swipe from the top of the screen and easily toggle on and off wifi, bluetooth, GPS, and other power saving options.
Share from anywhere
In a lot of iOS apps, you’re lucky to be able to share to Facebook or Twitter. From just about anywhere in any Android app, you can share to just about any app you have installed. For touchscreen operating systems, it’s about the next best thing to having a more traditional file system. It is huge.
Back key and context key
They’re right down there by your thumb for truly easy one handed operation. 
The app drawer
With Apple, by default every app is in your face and cluttering up one of your home screens until you decide to hide it or add it to a folder. With Android by default a newly installed app is alphabetically sorted, out of the way in your app drawer until you decide it’s important enough to look at on one of your home screens.