No difference.
And here's the proof.
The reason why there are two is that, %i is just an alternative to %d ,if you want to look at it at a high level (from python point of view).
Here's what python.org has to say about %i: Signed integer decimal.
And %d: Signed integer decimal.
%d stands for decimal and %i for integer.
but both are same, you can use both.
