Quantitative research generates numerical data using statistical techniques to objectively examine relationships between variables, employing deductive reasoning and answering "what" questions. It requires many respondents, uses structured techniques like surveys and observations, and analyzes data statistically. Qualitative research develops understanding of human behavior through subjective, holistic inquiry using inductive reasoning, answering "why" and "how" questions. It needs only a few respondents, uses non-structured techniques like interviews and discussions, and analyzes themes in the data. The key differences are that quantitative research is objective while qualitative research is subjective, quantitative data is numerical while qualitative data is textual, and quantitative examines causes while qualitative explores ideas.