Anyone with young children?

I have a problem I haven't been able to find on google
Is there a difference between a size 9 kids shoe and a size 9 toddler shoe? My sister in law said my niece took a size 9 kids/toddlers shoe. I found some really cute fat baby boots but I'm afraid to buy them. I want to get them soon and I can't get hold of my SIL. My niece is 4 years old if that makes a difference.

Here Hope this helps : )
Shoes.com Fit Assistant - Shoe Sizing Chart for Men, Women and Kids

Thank you so much. That makes more sense, I hoped there wasn't a size 9 toddler and a size 9 kids.

It's ok. I have small kids and I didn't even know. Lol