Data, data sets, and statistics are often used as an interchangeable term in daily conversation. In public health and other disciplines that use qualitative and quantitative analysis, data and statistics have two different meanings.
Data and Data sets are raw information that has yet to be processed for statistical analysis.
Statistics are data that have been analyzed often into rations, percentages, or figures/tables/graphs/visuals to showcase patterns, trends, and/or frequency.
Knowing which type of information you're looking for i.e., prevalence or incidence of a disease versus a strict count of people with that disease will help you determine where to look.
Many times you can get the raw data AND the statistical analysis by doing a search of your health outcome or disease on the CDC or NCHS websites, which are both linked on this guide.