What is the difference between Tresca and von Mises failure criteria?

Tresca (Maximum Shear Stress) criterion predicts failure when τmax = (σ₁ - σ₃)/2 ≥ σy/2, while von Mises uses distortion energy. Tresca is simpler but more conservative (by up to 15%). Both apply to ductile materials. Von Mises better matches experimental data and is standard in FEA. Tresca is preferred for quick hand calculations and conservative designs.