This is the literal translation of this famous Latin saying; the meaning is, that we can compare an old situation to a new one only after realizing that circumstances are not exactly the same, e.g. we can say that, mutatis mutandis, the political situation between the US and China is slowly evolving to the old cold war situation between the USA and the USSR; mutatis mutandis, i.e. knowing that there are significant differences between the two situations.