Experiencing an aroma gives rise to a more complex sensation than simply smelling, although both derive from an olfactory perception. We perceive the perfume on inhalation through the nostrils when we approach a cup of freshly prepared espresso.
The aroma is perceived through the channel that connects the mouth to the nose, allowing the beverage we have just drunk to release the entire richness of olfactory and taste sensations together. That's why the aroma is such a key component in describing the characteristics of a good coffee.