An example of an ontological distinction is the distinction between living persons and fictional characters of novels. Another example is the mind-body dualism of most Enlightenment thinking. Descartes claimed that there are two disjoint realms of existence, the realm of the body and the realm of the mind, but was not strictly a dualist because he saw imagination as the necessary linkage, and dreams as the necessary expression, of where body met mind.
Once certain distinctions are taken as basic, say in software architecture, they can be expressed as what is sometimes called a foundation ontology (computer science). This only expresses a limited concept of existence shared by only the users, and those affected by actions of the users, of the programs based on that architecture. Such distinctions may be simple or ordinary and need not be ontological, but the most basic may well be, and affect expression and action via the medium of that program. This is itself a controversy, as not everyone accepts simulation as capable of expressing any mode of existence.
The most important ontological distinction is that between the living and the dead. When a person dies, necessarily, their imagination and dreams are gone, and it is only memories of them, their writings or inspirings of others that remain. It may be difficult at this point to tell the difference between a dead person about whom biography is written, and a fictional person.
There is no clear and objective dividing line between an ontological, operational (part of a process) or ordinary distinction (part of culture). In many cases, one group claims a distinction to be ontological while others see it as far less important. Consider the impact of the claim of persons as fictional if those persons are widely followed as moral examples:
Theology tends to rely on assertions of the truth of the existence of founding figures (Rama, Krishna, Noah, Abraham, Moses, Jesus, Muhammad), and making an ontological distinction between divine inspiration, and ordinary acts or beliefs of these figures and their followers.
In this, theology tends to clash with philosophy, as the latter cannot admit argument by authority or accept formal hierarchy of the givers or transcribers of knowledge. Anyone must be equally able to reach the same level of skill at making distinctions. Lao Tse, Confucius, Muhammad and Buddha taught this, but, their own (reported) distinctions have risen to ontological status among followers, some of whom do not seem to recognize that they taught how to distinct, as opposed to what distinctions were to be made. Philosophy in general views such figures mostly as ethicists.
Another issue is that theology tends to see ontological distinctions regarding ethics as the most fundamental, whereas philosophy is more prone to see epistemology as prior to ethics. This may be the most crucial difference. It was often observed, e.g. by George Berkeley, that Roman Catholic thought put theology as the science of sciences whereas Anglican and other Protestant sects put philosophy there. This is itself a fundamental ontological distinction, that of how one makes such distinctions.
Some movements are devoted to challenging prevailing distinctions and social enforcements of them, even to the ontological level. Robert Anton Wilson reports that "the Dadaists, in total rebellion against the insanity of war and the general insanity of everything else, held poetry readings at which the poet was drowned out by other Dadaists with noise-makers. They had art exhibits where the audience was provided with axes at the door and told to destroy any paintings they didn't like. They held lectures in public urinals. In short, they began the "post-modern revolution against conventional "identities" and the language that divides things and people into classes."
Similarly the green movement attempts in a more disciplined way to break down some distinctions, while promoting others, notably awareness of waste as an evil and biodiversity as a virtue. This is one of many movements with a moral code competing with those of religion or science, and trying to address the process of making distinctions. Bernard Crick's list of the political virtues is an attempt to apply such distinction to politics.
Some movements, e.g. moral relativism, scientism, deny that any distinction has any prior moral status, and that only some, e.g. law or scientific method, are qualified to make major binding decisions - in which case the distinctions made by these in practice become ontological by default.
Extreme nihilism and some branches of anarchism deny that any ontological distinction matters at all, and view them as simple means to extend power (sociology).
See also: metaphysics