How do exothermic and endothermic reactions differ in reactor operation?

Exothermic reactions release heat, raising temperature unless heat is removed. Higher temperature increases rate but may reduce equilibrium conversion - requires cooling to control temperature and optimize conversion. Endothermic reactions absorb heat, lowering temperature without heat addition. Higher temperature favors both rate and equilibrium - requires heating to maintain rate. Exothermic reactions pose runaway risks; endothermic reactions are self-limiting but may need significant heat input.