When you buy goods from a particular shop or company, you are one of its customers. If you use the professional services of someone such as a lawyer or an accountant, you are one of their clients. Doctors and hospitals have patients, while hotels have guests. People who travel on public transport are referred to as passengers.

从某一家商店或公司买东西的人是他们的customer(顾客)。接受律师或会计师等的专业服务的人是他们的client(客户)。医生或医院接待patient(病人)，饭店旅馆接待guest(客人)。乘坐公共交通工具的人被称作passenger(乘客)。