Light roasts offer acidic, floral, and fruity flavors, more delicate aroma, and less body than dark roasts.
Dark roasts develop smoky, pungent, bitter, and carbonized flavors.
If one takes roasting to an extreme, completely bitter flavors develop. Over-roasted coffee is considerably hard to drink.
Green beans of same characteristics, which are roasted in different profiles, temperature, time and drum pressure, may be in the same color but shall not have the same aroma.
The foremost principle in roasting is to obtain the taste and aroma required by the roast master or the client.