I think it's normal to some extent for everybody to act differently at home than they do when outside their home comforts, but I believe it is more extreme with people with ASDs.
Firstly, saying, ''awwwww, look at that cute little animal'' to cute animals on the TV is something I hear NTs do a lot, admittedly women more so. My mum and her sisters do it all the time and it gets on my nerves. I do like animals but I don't keep shouting out how cute I think they are. It's really annoying.
I do act more childish, argumentative, hyper, angry, etc, at home. And when I'm out with friends or in public or at work, I act timid, placid, passive, shy, nervous, and laid-back. So basically, my friends can't imagine me being firey and aggressive and opinionated and immature, and my family can't imagine me being placid, laid-back, passive, and quiet.
So then I constantly get asked by my family how I can act so easy when I'm with my friends, but be so difficult to the people I love the most. I just don't know the answer.

I act the exact same way, and I don't know why. I try to make myself act more like I'm with friends when with my family but it doesn't really work. My family thinks I'm this one person who can't be calm and relaxed but I am.