O que significam as expressões: to be as different as chalk and cheese; to be poles apart

My brother and I are very different kinds of people. For example, he has always wanted to have a job that would put him in danger, so to speak, a job that involved some kind of physical work as well. That is why he applied to the Army one, but was rejected due to a health condition. Today he is a police officer and a very happy one. As for me, I've always wanted to mess with language and arts. When I was a child I wanted to be either a writer or a designer. Today, I am an English teacher. So I could say my brother and I are as different as chalk and cheese; we are poles apart.

When two people are as different as chalk and cheese or poles apart, it means they are extremely different. Stil talking about the expression to be as different as chalk and cheese, if you don't know what chalk is, chalk means giz in Portuguese. When the expression was created way back in the past, cheese used to be as white as chat. But for being very different in essence, they started to be associated with people that appear to be the same but are completely different. That's all for now. Take care!