An ontological distinction is an axiomatic distinction between agents.
eg: the belief in mind-body dualism.
(Compare with ordinary distinctions that are to do with state or behaviour).

Many such distinctions are combined into a schema or any broader ontology (computer science).

In programming or systems design, an ontological distinction is usually found in the constraints or domain analysis phase, while operational distinctions are left to last during programming itself (a series of yes/no switching and branching decisions, ultimately, when the program is compiled to object code). The "design phase" usually consists of ordinary distinctions, e.g. pseudo-code, mixed metaphors, weak analogies, that are not clearly or purely either ontological or operational in character, and do not bind directly to either the user's cognition nor the processor's machine code instruction set.