It is difficult to provide an exact number for how many different smells the human nose can differentiate as the human sense of smell is incredibly complex and varies from one person to another.

Scientists estimate that the human nose is capable of distinguishing between at least one trillion different odours. This estimate comes from a study published in the journal Science in 2014, in which researchers used mathematical modelling to calculate the number of possible odour combinations based on the number of odour receptors in the human nose.

This estimate represents the theoretical limit of the human sense of smell and does not necessarily mean that the average person is capable of distinguishing between one trillion different odours. Factors such as genetics, age, and environmental exposure can all affect an individual's sense of smell and their ability to detect and differentiate smells.

Indeed it would be difficult to count, let alone name 1 trillion, thats 1,000,000,000,000 different aromas. Needless to say how complex and subjective this range allows our own human sense of smell to be.