Ghetto and slum are referred to where poor people live or an urban area. The main difference between a slum and a ghetto is that a slum is a poor neighborhood, it is usually overcrowded, with closely packed bad housing unit with deteriorated or incomplete infrastructure.
A ghetto, on the other hand, is a poor neighborhood that consists of a specific race or religion. The word ghetto comes from the Jewish area in Venice (Venetian Ghetto in Cannaregio).
Some ghetto areas are developed due to political, social, or economic pressure. Ghetto and slum are usually prone to violence and drug abuse or other ill-mannered things. Slum can be used to refer to someone of a low class or something that is not befitting. For example, He looks slummed, hadn’t had his birth in weeks.