By definition, streets are often placed perpendicular to an avenue. Streets are relatively small side roads that branch off from an avenue, flanked by homes or buildings on either side. On the flip side, a typical avenue is a much larger main road, with trees, greenery, or other buildings on each side of it. You can think of streets as local paths that loop around your neighborhood. Then, you have a large avenue that runs across the main center of a town or city, which then splits off into streets.