If I am thinking of an apple, and I think of it as red, is that a different kind of red to the property of red a real object has? I would think that the property of red a real apple has is a real red, but the property of red a conceptual apple has is not real, its just imagination red. What kind of philosophy is this? Does anyone know where I can find information about it, in a book? Or website? Thanking you very much in advance.
Not certain I really grasp the true gist of what you are asking, at least without asking you to further define [your use of]the terms "conceptual", "property" and "real", but along similar lines, you may wish to explore Immanuel Kant’s transcendental musings. According to Kant, it is vital always to distinguish between the distinct realms of phenomena and noumena. Phenomena are the appearances, which constitute the our experience; whereas noumena are the (presumed to exist) things themselves, which constitute reality, what we call "the world". All of our [synthetic a priori] judgments apply only to the phenomenal realm, not to the noumenal. Because the thing in itself would by definition be entirely independent of our experience of it, we are utterly ignorant of the noumenal realm
As Ayn Rand put it:
“A concept is a mental integration of two or more units possessing the same distinguishing characteristic(s), with their particular measurements omitted.” (Ayn Rand, Introduction to Objectivist Epistemology)
Consider also this definition from wikipedia (the Aristotle definition I think):
A genus–differentia definition is a type of intensional definition, and it is composed of two parts: a genus (or family): An existing definition that serves as a portion of the new definition; all definitions with the same genus are considered members of that genus. the differentia: The portion of the definition that is not provided by the genus.
You are implying that the distinguishing feature of apples is that they are all red. Which is, well...not true. But let's assume that all apples would be distiguished from other fruits on the basis that they are red.
Then: the genus would be "fruit" and the differentia: "is of the color red (red is the dominant color)". However, since the particular measurement is ommitted, the particular value of "red color" is not included in the concept. It just has to has redness (and let's assume redness would be the domination of the red to other RGB colors, or whatever other way you want to measure/look at it)