Let $p$ be a prime, $s$ be a positive integer, and let $b$ be an integer satisfying $2 \leq b < p^{s}$ . In this paper, we obtain $b$ -symbol distances of all repeated-root constacyclic codes of length $p^{s}$ over finite fields. Using this result, we determine $b$ -symbol distances of all repeated-root constacyclic codes of length $p^{s}$ over finite commutative chain rings. We also list all MDS $b$ -symbol repeated-root constacyclic codes of length $p^{s}$ over finite fields, and all MDS $b$ -symbol repeated-root constacyclic codes of length $p^{s}$ over finite commutative chain rings in general.