What is a survey? What is a census? what is the difference between a survey and a census? A survey is the collection of information from all members of either a sample or a population.
A census is not easy to conduct since the size of the population is usually quite large.
It could also be very expensive if you are paying people to take these surveys.
The United States of America tries to obtain a census every 10 years. It fails every time since it is not possible to reach everyone.
For example, suppose you conduct a survey on incomes of those who graduated from Harvard University in 2000.
Suppose that 1500 students graduated from Harvard in 2000.
A census may be conducted here as long as the University kept the contact information of all 1500 students who graduated in 2000.
If the University does not have the contact information of all 1500 students who graduated in 2000, they may have to conduct a sample survey.