Learn English – What’s the difference in meaning and usage between “target” and “goal”

When used in reference to time, date almost exclusively refers to a specific 24 hour period that begins at midnight and ends at 11:59pm. When used this way, the date will be specified with a year (CE or BCE), the name of the month, and the number of the day within that month. The day number is a positive whole number that may be used in ordinal form (first, second, third, etc.) The name of the weekday is rarely referenced when referring to a date.

When setting up an appointment, you typically use the term 'date' if the appointment is a long time away or in a formal business setting. When making appointments with friends, especially if they are happening within one week's time, you would use the term 'day'.

You ask a friend "What day do you want to have lunch?" The receptionist at your doctor's office will ask you "What date would you like to have your next appointment?"

A client is the one to be served, economically or not, the economical one being a customer. A customer (purchaser) is not necessarily a client, when product(s) rather than services are offered.

A consumer is the one who uses products or services, paid or not. So, a consumer is not necessarily a customer. Children at toy shops are usually consumers, their mothers being customers.