This refers to getting stuck at a particular psychosexual stage due to excessive satisfaction or frustration. It's like being so obsessed with playing video games that you neglect other aspects of your life.
This involves unconsciously adopting the characteristics, beliefs, and actions of another person. Imagine if you start dressing and talking like your favorite celebrity - that's identification.
Introjection: This is incorporating the qualities or values of another person into your own ego structure. For example, if your teacher praises hard work and discipline, and you adopt these values as your own.