The main distinguishing feature of some fungi – which aren’t morphologically very different from each other – is scent. But people often have a terrible time articulating what they are smelling, and I think a lot of it has to do with culture – English is such a bad language for describing scents!
Example: at a mycological event in the fall, someone collected a mushroom that smelled very strongly of fenugreek. It smelled so strongly of fenugreek that I noticed the smell when I was walking by the table where it was and smelled each of the mushrooms in turn to determine which one it was – it clearly hadn’t been there the night before (it was collected during a morning foray). This particular mushroom was parasitized by another fungus, so it was not easy to tell what it was from its morphology. Also, it was not easy to tell what the parasitic fungus was because it was uncommon and the descriptions all 4 people involved in determining what it was were able to find were terse and not particularly helpful. At the end, we ended up not being able to resolve what was going on, because what I identified unambiguously as a fenugreek smell was identified by one other person as fenugreek but by two others as maple syrup. The fifth person brought in as a tiebreaker called it “spicy.” I suspect that most of the people who write mushroom IDs are not necessarily great chefs (or wine connoisseurs, or perfumers), so there’s a bit of ambiguity in the descriptions of the mushroom we thought it was, as well: some said it smells like fenugreek, some maple syrup, some “spicy and fragrant,” etc. (Fenugreek is used in fake maple syrup but real maple syrup does not smell like fenugreek. The chemical in question is sotolone, which is not in real maple syrup).
(I think that the mushroom that was parasitized was probably Lactarius helvus, the maple syrup milky cap – but it does not smell like real maple syrup, so I find the name annoying).