The Buddhist distinction between conventional and ultimate truth is frequently compared to Immanuel Kant's distinction between phenomena, things as they appear to a mind structured by categories of space, time and causation, and noumena, things as they are in themselves, and the comparison is worth examining for where it holds and fails.
Both distinctions agree ordinary experience presents a structured world not identical with how reality is "in itself," and both hold that recognizing the distinction changes what claims can be made about ultimate reality. But they diverge on what lies on the deeper side of the line. Kant held noumena are strictly unknowable, existing but permanently inaccessible, a stable if unreachable reality behind appearances. Madhyamaka's ultimate truth, emptiness, is not a hidden reality behind appearances; it is, as the main entry states, the truth about the very things conventional truth describes, that they lack inherent existence, so ultimate truth is a way of correctly characterizing the same conventional things rather than a further layer of them.
This matters for practice: Kantian philosophy offers no method for accessing the noumenal realm, whereas Madhyamaka holds that ultimate truth, precisely because it is not a separate hidden object, can be directly and meditatively realized, the entire soteriological point of the doctrine. Comparative philosophers conclude the resemblance is real at the level of noting appearance and reality can diverge, but the two traditions build entirely different architectures on that shared observation.