Why don't all types of brass have identical properties

All types of brass don't have identical properties because brass is not a pure metal but is primarily an alloy made up of copper and zinc.

Explanation:

Brass is a mixture of compounds or an alloy composed of copper and zinc combined at various proportions. Generally, copper percentage varies from 55%-95% with zinc by 5%-40% by weight of brass.

According to the percentage of composition of its elements, (Zn and Cu), different varieties of brass with different properties are formed. Like, although the general color of brass is bright gold; with high amount of copper the brass color gets a rosy tinge, and with high amount of zinc it gets a silvery tinge.