Census collects data from the entire population, while sampling collects data from only a subset of the population. Sampling provides results more quickly and at lower cost but with less accuracy than a census. Probability sampling methods like simple random sampling, systematic sampling, and stratified sampling allow determining the probability of selecting samples, while non-probability methods do not. Both methods have advantages and disadvantages related to accuracy, costs, and ability to generalize to the total population. Errors can occur from how samples are selected and from other issues in data collection and processing.