Science has to do with the systematic study of the natural world through observation and experiments as well as the behavior of the physical aspects.
Pseudoscience is based on a collection of beliefs or practice such as horror scopes or palm reading for example the people would like to believe are true but cannot be scientifically proven.
The relationship between the two co-exist to help explain the world around us rather it can be by facts or not, it still tries to best explain the natural world.