Let \(T_n\) denote any rooted tree with \(n\) nodes and let \(p = p(T_n)\) and \(q = q(T_n)\) denote the number of nodes at even and odd distance, respectively, from the root. We investigate the limiting distribution, expected value, and variance of the numbers \(D(T_n) = |p – q|\) when the trees \(T_n\) belong to certain simply generated families of trees.