Final answer:
PMM stands for Perfect Market Model, a theoretical model in economics, and GMM stands for Generalized Method of Moments, an econometric estimation technique.
Step-by-step explanation:
PMM stands for Perfect Market Model, which refers to a hypothetical market structure that assumes perfect competition where no individual buyer or seller has the power to influence the price of a product. In contrast, GMM stands for Generalized Method of Moments, which is an econometric technique used to estimate parameters in models characterized by a set of moment conditions derived from economic theory and assumptions.