The first is called a “significant other,” which is someone about whom we have some degree of specific knowledge and we therefore pay attention to what we perceive to be his or her personal thoughts, feelings, or expectations. Here, significant does not mean that the person is important.
The second type of other is the “generalized other,” which we experience primarily as an abstract social status and the role that goes with it.
Example of a "generalized other": When we enter a grocery store without any knowledge of the grocer, our expectations are based only on knowledge of grocers and customers in general and what is usually supposed to take place when they interact. Thus when we interact with this grocer, our only basis for knowledge is the generalized other.