The short answer is both terms are different and describe different things about moisture in the air. The dew point is another temperature value. It is the temperature air needs to cool to become ...

The dew point is the temperature that the air would have to be cooled to (at constant pressure) in order to reach saturation. As the temperature drops to the dew point, water vapor molecules condense.

MIKE MOSS SAYS: Barry, The trick here is that the relative humidity (RH) at the altitude where rain is being produced IS always 100% when rain occurs, but this altitude can be many thousands of feet ...

Humans, microbes (bacteria, viruses, fungi), and plants all react differently to dry ambient conditions. Microbes adapt quickly by shrinking down, forming thicker membranes, and becoming dormant.