Repressive State Apparatus is being able to control something through the threat of violence. A reason why Althusser could call it repressive is because reprieve is power. It is someone being able to control what others are doing and it is usually by force. An example would be the police. We are able to understand his words since usually police have power to be able to do as they please since most people are scared of them or know they don’t have much of a say since there is a power dynamic. 

Ideological State Apparatuses is when police, court, and prison only step in when something fails to put people in their place. It prevents change to status quo. It seems to work by ideology. Their society is based on beliefs and values. 

Repressive and Ideological State Apparatuses are different from each other because Repressive State Apparatuses is force with punishment or violence and Ideological State Apparatuses is society exist naturally by status quo. The difference between them is Ideological State Apparatuses shapes beliefs for status quo and the other enforces undergoing commands.