Friendships not the same as other peoples

I'm a student at university and have quite a few different friends as well as a best friend but what I can't understand is why they all act completely differently around other people to me. When we're in larger groups I tend to be really quiet and not say much and everyone else is super chatty and says random stuff I myself don't find particularly interesting. I have deep relationships with some of my friends, and we talk about more normal stuff when its just the two of us, but as soon as anyone else joins in its like they're totally different people. Like they start showing random memes and stuff on their phones to each other or make jokes that I don't find funny, none of which remotely interests me in the slightest. I have known some of these people for 12+ months now and they have never mentioned it me, like they're not even aware that I am different to them.

When I met my best friend we got on really well and still do, but when we first hung out with other people it was like he was a totally different person, one that I don't connect with as much. I don't know if its a good thing that my friends are different around me as it allows them to show sides they wouldn't to other people, or whether they feel they can't be a certain way around me because they know I don't care for that?

Also I am fully aware that I am different to other people, I just don't get why people are so cool about it. It amazes me that they don't find me boring or judgemental.