He is my brother vs He is a brother of mine

[Tan Elaine]

He is my brother.
He is a brother of mine.

Is there any difference in meaning between the sentences?

Thanks.

 

[Roman55]

I am not a teacher.

There is no difference in meaning but, 'He is a brother of mine' is very unnatural.

Perhaps if you had a LOT of brothers and he is one of them, but even so...

 

[emsr2d2]

He is my brother.
He is one of my brothers.

I find "He is a brother of mine" very unnatural.