Theory, Model, Method
A theory is a system of hypotheses for describing and/or explaining a certain area of objects. Each theory must satisfy certain requirements, such as consistency, completeness, adequacy, simplicity. It must be falsifiable in principle.
A model is a formal representation of the structural and functional characteristics of an object of study. Models are used in order to explain a theory, to simulate a process or to illustrate the functioning of an object of study.
Model of speech production (Levelt, 1989)
Exercises on Linguistic Theories and Models