Anaerobic respiration yields more ATP. The 2 ATP produced by substrate-level phosphorylation in glycolysis represents the total energy yield of fermentation. NADH passes its "high-energy" electrons to pyruvate or a derivative of pyruvate, recycling NAD+ and allowing glycolysis to continue.
Anaerobic respiration uses an electron transport chain to capture the energy of the electrons in NADH via a series of redox reactions; ultimately, the electrons are transferred to an electronegative other than oxygen.
And additional molecules of NADH are produced in anaerobic respiration as pyruvate is oxidized.