An easy example to understand the diffrence ..
بَعدَ أذُنِكَ after your ear
بَعْدَ إذْنِكَ after your permission
but if you have this situation
you can't even a native can't distinguish if it's ear or permission
only if it's clear in the context ..
but if you find it like
بعد أذنك it's 99% refering to ear
this is why it's wrong to write it like اذنك
So the Summary and the result , yep , there is a diffrence between أذنك and اذنك
but don't complain a lot about it , it will not create a big problem after all :)