

I’m not sure what you’re asking which of. I might have not worded the last part of my comment unambiguously
To rewrite:
I don’t think you can tell Linux from a Unix by looking at it reliably. Though in general unixes are tidier, there are Linux users that are just as tidy and keep their system just like a Unix one

Tit just used to mean small. That’s how the word came to be used for some boobs, then all boobs. Perhaps teat (nipple) got shortened also, but the bird is named for being small
There’s also the titmouse which is littler than other mice