The distinction between imagination and seeing is regularly blurred, most commonly in dreams, but also on psychedelics or quasi-psychedelics (e.g. cannabis), and also in altered spiritual states (meditative practices).

The two experiences are different, most of the time, yes, but only "completely 100% different" IMO to aphantasics, or those who are high in aphantasia. I.e. hyperphantasia is a thing, and a normal thing for most people in altered states (and schizophrenia might be seen as involving an extreme form of hyperphantasia intruding where it shouldn't, in some cases).