Brass, copper, and bronze are all copper-based alloys, but they differ in their composition and properties. 

Brass is an alloy made from copper and zinc. It is widely used for decorative purposes because it has a bright gold-like appearance. Brass is also strong and has good corrosion resistance. It is commonly used in plumbing and electrical applications, as well as in musical instruments, locks, and doorknobs.

Copper is a pure metal that is known for its excellent electrical conductivity, ductility, and corrosion resistance. It is widely used in electrical wiring, plumbing pipes, roofing, and industrial machinery parts.

Bronze is an alloy made from copper and tin. It is hard and durable, making it ideal for forging and casting applications. Bronze has a reddish-brown appearance and is used for making art, sculptures, and jewelry. It is also used in coins, bearings, and springs.

In summary, brass is a zinc-copper alloy used for decorative purposes, copper is a pure metal used mainly for electrical and plumbing applications, and bronze is a copper-tin alloy used for art and industrial applications.