If there is a ~ between two or more things, they are similar to each other.
The astonishing ~ between my brother and my first-born son...
She is also 25 and a native of Birmingham, but the ~ ends there.
N-UNCOUNT: oft N between/in/with n
Similarities are features that things have which make them similar to each other.
There were significant similarities between mother and son...
N-COUNT: usu pl, oft N between/in/with n