Mum & Younger Sister

I'm trying to understand something. I'm a very intuitive person. Usually spot on, get what's happening with people without them saying much.
However this is a case that I can't seem to understand and want to help. I want to help them understand each other better. I've had them sit down and talk but it came to the same conclusion. I'm the older sibling. My younger sister and mother can't seem to get along. Blood related. Same childhood. No trauma.
Both are cautious around each other. I can get both sides of it, my mothers very truthful and my sisters stubborn and independent like my mother taught us to be as we grew up. Polar opposites maybe, but they're still, idk.
I just want them to get along because everytime they're together and I'm there, there's arguments.
I want their relationship to get better or something where it doesn't result in an argument because they love each other but something is just making it hard for them to get along.
I want to help and can usually understand things but in this case it's just hard.