They really do taste different. Try a French roast vs a light roast some time if you want an extreme example, or a very tart wine and a very sweet one. The outliers at each end of the spectrum are very different.
If you can't tell which is which in those cases then you might legitimately have a problem with your sense of taste.
If you can't tell which is which in those cases then you might legitimately have a problem with your sense of taste.