A street is a public way on which people travel, typically one that is paved or made of concrete. Streets can be residential, commercial, or industrial, and can vary in size from small, narrow lanes to wide, multi-lane highways.
A road is a paved or improved strip of land that connects two or more places. Roads can be rural or urban, and can vary in size from small, local roads to large, national highways.
An avenue is a wide, tree-lined street, often found in cities. Avenues are typically larger than streets, and are often used as major thoroughfares.