Maybe because you’re closer in age and have the same interests. Parents and kids don’t always see eye to eye.
Why is it me and my sister get Along better than me and my mom? We don’t talk about religion crap and just laugh? Why is that?
You actually answered your own question.... She doesn't talk to you about religious crap.
Because that's just what sisters do, they have a tendency to get along better with each other then they do with their mother.