Counterexamples to uniqueness are not hard to find. For example, $36=(2)(3^3)-(2)(3^2)$, and $36=(5)(2^3)-(1)(2^2)$.
Already even if we stick to the single prime $3$, we can express $36$ in infinitely many ways as $(a)(3^3)-(b)(3^2)$.
Counterexamples to uniqueness are not hard to find. For example, $36=(2)(3^3)-(2)(3^2)$, and $36=(5)(2^3)-(1)(2^2)$.
Already even if we stick to the single prime $3$, we can express $36$ in infinitely many ways as $(a)(3^3)-(b)(3^2)$.