What are the differences between an approach and a theory?

These two concepts relate to scientific research and understanding, though in different ways. A theory is an explanation for how facts relate to one another, while an approach is a methodology for obtaining those facts in the first place.

A theory is a framework for understanding relationships between observable facts. In other words, they explain observations. Hypotheses become theories when enough data is gathered to support the hypothesis. Theories are mutable, and can be strengthened or weakened based on new information that is observed. It’s important to note that the facts themselves won’t change, but rather the explanation of the facts. Jamie Tanner, professor of biology at Marlboro College, explains the relationship between theories and facts as follows:

For example, we have ample evidence of traits in populations becoming more or less common over time (evolution), so evolution is a fact but the overarching theories about evolution, the way that we think all of the facts go together might change as new observations of evolution are made.

An approach, on the other hand, is the framework and context with which somebody conducts research. It can refer to both the method of interpretation used as well as the actual type of research conducted. For example, if investigating mental illness, an anthropologist would consider the context of the communal norms, a sociologist would consider the context of interaction between individuals, and a psychologist would consider how mental illness is experienced by the individual.