A generalist can live in a wide range of environmental conditions. They may have more tolerance for a breadth of food, or temperature or other factors. A specialist speices can only thrive in a narrow range of environmental conditions, or on a narrow diet or conditions. Specialists have less capacity to cope wit the change in the environement. A specialist may only survive on one type of food, or survive on a certain amount of rainfall. Generalists generally have more capacity to change.
Humans are generalists when it comes to food because of the wide variety of food we can tolerate. An example of a specalist trait is a koala bear that eats eucalytpus, without eucalyptus the koala
s eating choices would be narrowed.