First: Most "taste" is smell!
In general, very different molecules can taste/smell the same,
but this is not very common.
But the main "problem" You speak of arises from natures "laziness".
Something proved good, is used throughout all flora and fauna.
This is true for a lot of chemicals in nature, including aromas.
Especially in biologically related plants You will find always the same compunds,
only the mixture ratios differ. Nevertheless You can differentiate the taste.
Georg