Vanilla bean != Vanillin, since the smell of natural vanilla bean has a many more components to it other than Vanillin which lend it that characteristic odor (sweet, animalic, slightly woody and herbaceous).

Vanillin by itself is of course a principle component. However, coumarin and vanillin don't smell too similar. Coumarin has more of a herbaceous, 'hay' smell, quite different from vanillin itself.