We geeks often have our own ways to express, which might be too geeky for normal people to understand.
Here are some general guides to help you communicating with your geek friends (at least knowing what they are thinking about… )
1. “X is a subset of Y.”
Spoken by Computer Scientists to say that X is a kind of Y, but Y is not X.
Real life examples:
“Matcha is a subset of Green Tea. They are different!”