In order to understand the difference, you'd have to have a blinded and unblinded study, and compare the results. Then you could understand the difference between a guess with 90% confidence and actually knowing what treatment you received with certainty.

It seems reckless to presume the difference (between blinded and unblinded) is small. The numbers you cite (94.7% and 90% confidence) have nothing to do with the question you're trying to answer.

For example, an important difference may be with respect to expectations. If you're told you're receiving a psychedelic treatment, you may go into the experience with different expectations than if you were unsure about what treatment you were getting.