Homo Sapiens Sapiens abbr. Humanity likes keeping things simple. Can't handle complexities, these primeval apes. Bum scratching monkeys, who can hardly differentiate Madonna from Nuclear Fusion, now desire to differentiate the 'Real World' from the 'Imaginary World'. (Morpheus mama would've been prouuud. Extremely!)
Real World Imaginary World, what's the fucking difference, one might ask.
Well waddaya know, there's none.
(The Wachowski Brothers, for god knows what reason, didn't seem to share my views and as a consequence gave the world 'The Matrix Trilogy' which amongst others did wonders at the box office. Guess you can indeed mint money by disagreeing with me. Now there's a revelation!)
On a more serious note, mankind has fallen prey to a reductionist approach to life wherein objects, concepts and even philosophies themselves are understood by breaking them down into constituent parts. The drawback is that one cannot understand, or for that matter even see the way these constituent units interact with each other to make the whole (of the universe or world or whatever) that we exist in.
Similarly, the concept of differentiating the real world from the imaginary world is an exercise to understand two aspects of human existence without considering them as a tightly integrated unit. The real world and the imaginary world are the two constituents of a better world, a more meaningful existence. Two sides of the same coin... One can believe it possible to view everything as something maybe not that simple, but as something seamlessly integrated. A greater concept.
Just the way two numbers - one real, one imaginary, make a complex number.