The world is real for Ignorant people, while it is unreal for a Jnani says Patanjali yoga Sutra 2.22.
The world is an illusion has to be experienced. If you merely say or convince yourself with tarka (logic) like a NyAyika (person following nyAya), then it is just an empty talk.
It is like seeing snake, but saying I see rope. It is not that the teachings are false. They are true, but they have to be realized. Here the path begins. sAdhanA is for removal for ignorance.
Hence we have to take relative reality (vyavahArika satya) and absolute reality (pArmArthika satya).
Real is that which is present at all times and is eternal. All end in Jnana except Brahman. I think for practical purpose this explanation is useful.