304 and 316 stainless steels are both widely used in various applications due to their corrosion resistance and other desirable properties, but they have some differences:

Composition:
304 stainless steel contains around 18% chromium and 8% nickel, with small amounts of carbon, manganese, silicon, phosphorus, sulfur, and nitrogen.
316 stainless steel contains about 16-18% chromium, 10-14% nickel, 2-3% molybdenum, and smaller amounts of carbon, manganese, silicon, phosphorus, sulfur, and nitrogen.

Corrosion Resistance:
Both grades offer excellent corrosion resistance, but 316 stainless steel is known for its superior resistance to corrosion in harsh environments, especially in chloride-containing environments like coastal areas or near industrial sites.

Applications:
304 stainless steel is commonly used in kitchen appliances, food processing equipment, architectural trim and molding, automotive parts, and industrial equipment where corrosion resistance is required but not critical.
316 stainless steel is preferred in applications where exposure to corrosive chemicals or saline environments is expected, such as marine environments, chemical processing plants, pharmaceutical equipment, and medical devices.

Cost:
Generally, 316 stainless steel is more expensive than 304 due to its higher nickel and molybdenum content.
Machinability:
304 stainless steel is easier to machine than 316 stainless steel, which can be more difficult due to its higher hardness and toughness.

Temperature Resistance:
Both grades can withstand high temperatures, but 316 stainless steel has better resistance to high temperature and maintains its strength at elevated temperatures better than 304 stainless steel.

In summary, while both 304 and 316 stainless steels offer excellent corrosion resistance and are versatile materials, the choice between them often depends on the specific requirements of the application, such as the environment, temperature, and budget.