5S to 4S iTunes restore

[duggram]

What happens to existing data and apps when you restore a 4S with a 5S backup?

The charging port on my 5S quit this weekend. I tried all the tricks I could find on the Web to get it working but it never did start charging. I'd like to wait for the next SE before deciding on which phone to get to replace the 5S. So I got my very old 4S put on my line and used it today. Now I'd like to get the 5S data from iTunes and restore (?) it to my 4S. What is going to happen when I hook my 4S up to my MBP and restore it?

 

[eyoungren]

What happens to existing data and apps when you restore a 4S with a 5S backup?

The charging port on my 5S quit this weekend. I tried all the tricks I could find on the Web to get it working but it never did start charging. I'd like to wait for the next SE before deciding on which phone to get to replace the 5S. So I got my very old 4S put on my line and used it today. Now I'd like to get the 5S data from iTunes and restore (?) it to my 4S. What is going to happen when I hook my 4S up to my MBP and restore it?

The issue is not based on device, it's based on the version of iOS.

iOS is the same across devices, just different features apply to whatever device it's installed on.

So, what matters is your version of iOS.

You cannot restore a device on older firmware to a backup made on newer firmware.

For example, let's say your 5s is running iOS 10.3.3. The highest firmware your 4s can run is 9.3.5. Since what I said above is true, you cannot restore a iOS 10.3.3 backup to a device running 9.3.5.

But if say your 5s is running 9.3.5 or perhaps an earlier version then your 4s could restore to it (again assuming your 4s is running 9.3.5).

Does that make sense?