Question

what is difference between science and natural science

Answer 1

Natural Sciences (NST) is a branch of science concerned with the description, prediction, and understanding of natural phenomena, based on observational and empirical evidence
Social science is a major category of academic disciplines, concerned with society and the relationships among individuals within a society. It in turn has many branches, each of which is considered a "social science

Answer 2

Science is the field of giving rigorous answers, but ironically the definition of "science" is itself not rigorous.

Science is:

Processes for creating models for reliable prediction and control of the natural world;

Models created using those processes; and  

Application of those models.