It's also what each OS can do. I have an iPad mini. It deals with vector images which are scalable. I haven't seen much on Android that uses vector as a general format. I use SVG for crafting. The iPad also lets me save episodes of one of my craft sites videos on the tablet. I can watch the instructional video whether or not I have a wifi connection. You can get the same app on Android, but you can only stream live.
Other small differences I've noticed - MLB At Bat has more control over the game than Android. The only thing really missing now is "jump to inning" like on a Roku. I've also been impressed with the iPad's printing. I have to fuss with the phone to get the Samsung laser to print what I want.
I just told the iPad to print a recipe I forgot to print from a different room, and it printed. Sitting in the out tray the next morning. With the phone, I wind up having to keep pressing the wifi on button. To be fair, that's mostly Samsung. I've had no trouble with the Canon Selphy or the Brother color laser on android.
I bought the mini just for the vector progams. The Acer tablet didn't have a gyroscope so my astronomy programs with live view wouldn't run.
I will say though, that Android has a far better selection of apps. There's a large selection of Roku apps you can try - ad supported but free. If you like you can buy and get rid of ads. Apple's choices contain far more paid apps and so far, I haven't seen any way to try any out. The free apps also seem to have loud, noisy and in your face advertising. I tried out a solitaire game and after playing 2 games, you would get a full screen ad with the volume blasting. This is no good in the middle of the night.
Like Android, you can family share an app.