A census gathers information from every entity in a population. As a result, data is accurately representative of the whole population and detailed data can be made available right down to small areas.
In a survey, however, only part of the total population is selected. Surveys are generally conducted on a nationwide basis and produce data at a national, state and sometimes regional level.
The advantages of a census include accuracy and detail. However, they are also expensive and time consuming. Collecting data from a larger population involves lengthy analysis and a longer publication time-frame.
When conducting surveys, on the other hand, fewer questionnaires are sent which means there is comparatively less data to process. But, since surveys do not represent the entire population, they are not quite as accurate or reliable.
So while census and surveys both involve data collection, they differ in their objectives and practice. Before deciding which one to conduct, think about your analysis needs and about which is a better fit.