This document discusses and compares absorption costing and variable costing. Absorption costing treats both fixed and variable manufacturing overhead as product costs, while variable costing treats fixed overhead as a period cost. The key difference is in the treatment of fixed overhead. Absorption costing is required for external financial reporting and taxes, while variable costing is better for internal decision making by separating fixed and variable costs. The document also notes some potential problems with using absorption costing for internal analysis.