Olfactory research in humans has largely focused on odors perceived via sniffing, orthonasal olfaction, while ignoring odors perceived from the mouth, retronasal perception. Prior work on retronasally presented odors use animal models and focus mainly on odor sensitivity, but little is known about retronasal olfactory perception and cognition in humans. In this study, we compared orthonasal and retronasal odor presentation routes to investigate differences in odor descriptions. Thirty-six individuals participated in a within-subjects study using twelve odors (varying in pleasantness and edibility) in perceptual and semantic tasks. As expected, we found route-dependent differences in perceptual odor quality (pleasantness, edibility, and familiarity ratings), and a better ability to identify odors during orthonasal presentation. Additionally, more concrete (and source-based) language was used when describing odors presented orthonasally. Exploratory analyses revealed that while orthonasal odors were described with words that had visual associations, retronasal odors were described with words that had tactile associations. Interestingly, sensitivity and intensity did not explain these observed route-dependent differences in descriptor usage, suggesting cognitive and linguistic processes differ between odors presented orthonasally and retronasally. Our results show that olfaction is in fact a dual sense, in which the routes change the perception of an odor.