Why do I feel more comfortable telling my best friends my secrets than my other friends?

I mean I’ll talk to my other friends but if I have a problem, I just can’t tell them but when it’s my two best friends, I’m more comfortable telling them. My other friends got mad at me for not telling them and they said all you can trust us. They told me that was messed up I told my best friends but not them and they’re my friends too.