I’ve been a weed fan for 30 years and I cannot tell the difference at all. In fact, from what I’ve read, the THC that THCa turns into as it’s being smoked is identical in every way to any other THC that develops in marijuana.
My friends and I, all long time users, have done several blind tests and can’t tell a difference. Make sure you are comparing the same strains when you do your blind tests, otherwise you will inadvertently be testing the differences between strains. Various strains of cannabis have very pronounced differences in flavor and effect in my experience.