What is the difference between ordinary bolts and high-strength bolts?

Ordinary bolts are generally made of ordinary carbon structural steel without heat treatment. High-strength bolts are generally made of high-quality carbon structural steel or alloy structural steel, and need to be tempered and heat treated to improve the comprehensive mechanical properties. High strength is divided into 8.8, 10.9, and 12.9.

From the strength grade: 

high-strength bolts are commonly used in two strength grades: 8.8 S and 10.9 S. Ordinary bolts are generally 4.4, 4.8, 5.6, and 8.8.

From the force characteristics: 

high-strength bolts apply pre-tension and transmit external force by friction, while ordinary bolts transmit shear force by bolt rod shear resistance and hole wall pressure.