This is an excellent question.
A. One way to motivate your question is to compare:
(1) laws of nature
(2) the things they act on (Essentialism?)
These really do seem to be in different ontological categories. Without such a difference in categories, it seems that things would cause things and one would get an infinite regress.
B. Another way to look at this is through the idea of relations; see D.M Armstrong's remark:
Philosophy has been a long time coming to grips with the category of relation. Aristotle said of relations that they were "least of all things a kind of entity or substance" (Metaphysics 1088 a 22). The tradition has tended to echo this ever since. The categories of substance (thing) and attribute (property) are long established, but not so the category of relation. It is not until the late nineteenth and the twentieth century with C. S. Peirce, William James, and Bertrand Russell that relations begin (no more than begin) to come into focus. (Universals: An Opinionated Introduction, 29)
It is curious that we have the following at WP: Relation § Logic and Philosophy:
• Relation (philosophy), links between properties of an object
And yet, when the link is clicked, one is redirected to WP: Property (philosophy). The very idea of 'property', at least to me, does not smell like 'relation'. This is but a noisy indicator that relations are still not dealt with head-on in philosophy. See also the Google search for "site:plato.stanford.edu relation", with really only one result which directly bears on relations: Medieval Theories of Relations.
C. I think it is revealing to look at what a popularizer of science, Caltech's Sean Carroll, has to say at Post-Debate Reflections (the debate was with William Lane Craig):
The cosmological argument has two premises: (1) If the universe had a beginning, it has a transcendent cause; and (2) The universe had a beginning. [...]
My attitude toward the above two premises is that (2) is completely uncertain, while the “obvious” one (1) is flat-out false. Or not even false, as I put it, because the notion of a “cause” isn’t part of an appropriate vocabulary to use for discussing fundamental physics. Rather, modern physical models take the form of unbreakable patterns — laws of Nature — that persist without any external causes. The Aristotelian analysis of causes is outdated when it comes to modern fundamental physics; what matters is whether you can find a formal mathematical model that accounts for the data. The Hartle-Hawking “no-boundary proposal” for the wave function of the universe, for example, is completely self-contained, not requiring any external cause.
What we see here is equivocation:
(i) laws of nature
(ii) unbreakable patterns
One of these exhibits causality, while one does not.
D. You may also like what Bernard d'Espagnat has to say about why (1) exist:
Things being so, the solution put forward here is that of far and even nonphysical realism, a thesis according to which Being—the intrinsic reality—still remains the ultimate explanation of the existence of regularities within the observed phenomena, but in which the "elements" of the reality in question can be related neither to notions borrowed from everyday life (such as the idea of "horse," the idea of "small body," the idea of "father," or the idea of "life") nor to localized mathematical entities. It is not claimed that the thesis thus summarized has any scientific usefulness whatsoever. Quite the contrary, it is surmised, as we have seen, that a consequence of the very nature of science is that its domain is limited to empirical reality. Thus the thesis in question merely aims—but that object is quite important—at forming an explicit explanation of the very existence of the regularities observed in ordinary life and so well summarized by science. (In Search of Reality, 167)
For more, see his On Physics and Philosophy; you might be able to make some sense out of a bit from his conclusion, pp410–411.