Why are there not a lot of study like science and social?
It is not completely clear what you are looking for help with in this question, but I will do my best to help you. There is extensive research on social sciences. Some of the research is psychologically based and looks at how one variable affects another variable or looks to see if there are correlations between two behaviors that we can observe. Other research is on social science itself looking at how the systems we live in (macro, mezzo and micro) affect the decisions people make. An example of this would be how poverty affects education or teen birth rates.
If you are looking at the difference between the definition of science and the definition of social science, then you are looking at how science follows the scientific method to find answers in regards to the relationship between variables, gather data and test theories. Meanwhile social science focuses on human observation and looks for biological or enviromental causes for that behavior but often does not follow the scientific method to obtain an answer.