In the UK -ie is pretty much firmly a diminutive. Eddie, short for Edward, or Edwin, in the case of my bro. Eddy is a whirlpool. But it's not hard and fast. 'Kiddie' is an interesting one for me. It's an old Sussex word meaning something like 'bloke', 'chap', 'fellow', with no sense of youth. I remember it from a chap (kiddie) teaching at Plumpton Agricultural College in 1986. The story's too long. But I know a few chaps who still use it, none of them younger than me and all from a very specific part of Hastings. eg 'You know, that kiddie who does the plastering for John.' Shyheels lives mere miles from me, but I bet he's never heard it in that sense. It's a usage dying.
The newest Harper Lee book finally allowed me to understand To Kill a Mockingbird. We South Saxons have a motto. Sussex will be Sussex, and Sussex won't be druv. We have music too. https://www.youtube.com/watch?v=4lGxD6cxMKM I feel so at home to sit by a bandstand and hear Sussex By The Sea.
I don't really mean to digress, but to make a point about regional differences. I believe there's a wealth in the regional, but that the national and international standard needs agreed punctuation and grammar. Register is all important. I wouldn't speak Sussex to the Queen.