While data and statistics are often used interchangeably, there are important differences between all three.
I know. That sounds weird but trust us it's grammatically correct. Data (plural of datum) are individual pieces of factual information recorded and used for the purpose of analysis (its interpretation and presentation). They refer to a set of values, which are usually organized by variables (what is being measured) and observational units (members of the sample/population).
Essentially, data are the raw information from which statistics are created.
Demographics deal with population. They're the statistical characteristics of human populations (such as age or income) used. This can be applied to varying scales (neighborhoods, counties, countries, etc.). It is inherently socio-economic in nature.
In sociology, "demographic" can also be used as an adjective relating to the dynamic balance of a population, especially with regard to density. A "demographic trend," for example, is any measurable change in the characteristics of a population over time.
Demographic data, then, refers to socio-economic observations and variables about a population. Demographics is the result of statistical analysis of said data.
Statistics, in this case, is a collection of quantitative data, the result of its analysis. In other words some computation has taken place that provides some understanding of what the data means. Statistics are often, though they don’t have to be, presented in the form of a table, chart, or graph.