Social psychologically oriented survey research frequently asks why and how questions, and descriptive qualitative research concentrates on what questions.

I would prefer the more traditional distinction between quantitative as based on closed-ended questions with numerical data, and qualitative as open-ended questions and observations with textual data.

Qualitative research explores answers to “how”, “why” and “what” aspects of questions because it gives details of events and reasons of happenings. In the case of Quantitative research is concerned with quantification, replicability, objectivity which is tailored towards positivist idea of research.