This is a good and important question. I think it deserves a proper answer. I will try to keep it short.
Take these three words, existence, reality, matter, do they mean the same thing? Ask five different people and you will get five entirely different answers.
Here is how I use these words:
Existence is the broadest of the three. It means "everything." To make it clear, it means "everything that is," but that is actually redundant, because what "isn't" is nothing.
Reality also means everything that is, but has this distinction. The correct definition of reality is, "all that is, the way it is." The classical logicians talked about "modes" of existence, and it is that concept that is meant by the phrase, "the way it is." What it means is this: rocks, trees, people, all exist as material entities, but history exists too, as does science, but they do not exist as material entities. Dostoevsky also exists, but only as a historical figure, and Stavrogin also exists, but only as a fictional character in one of Dostoevsky's novels. These things all exist and are real, but they to not exist in the same way and their reality is only true if the way they exist is specified.
Is Stavrogin real? Yes, if you mean as a character in one of Dostoevsky's novels. No, if you mean as a historical character.
At this point, I can address your question about perception, and how we can know something if we do not directly perceive it. We do not directly perceive anything of history, yet we can know a great deal about it. We could not know anything about it without perception, and whatever we know about it came by way of perception (for example of the words in the book we read about it), but we cannot directly perceive anything in history. This is obviously true of fictional characters as well.
The examples of science are even better. Almost everything in modern science is incapable of being directly perceived. All we know about the sub-atomic world comes through perception, but we cannot directly perceive anything of that world.
By matter I mean, material existence, and by material existence, I mean, that existence we are directly conscious of, and by conscious of, I mean "perception." It should be obvious that the material existence we are directly conscious of is real, but not all of reality, since reality includes everything that exists, past, present, and future, including our most abstract concepts (as those in science and history) as well as fictions, so long as the nature of their existence is made explicit.
Hank
Well done. Now that you've explained your vocabulary, I agree with it.