psychology 和 mentality 的差別在哪裡？如果不好說明，請提供一些例句。

Psychology is the study the mind. In that sense, it can refer to the overall thought processes of a person. It's meaning is more abstract and loose.
For example, "I am interested in how people think when they are committing a crime, so my major is Criminal Psychology."

However, a mentality is much more specific. Mentality refers more to a set of beliefs that a person participates in.
For example, "All of these people shouting angrily outside of the bank have a mob mentality!"