The main diference is the purpose of research. If you want to answer the questions that are started from " who" " how many" " how often" etc. You should use a qulitative researces. You collect the information and then explain it via statistic methods. You receive a result in view of graphic or diagramms ( for example you col know the share of the market for your product) . The quantative researches help you to answer the question " why"( why do the people don't buy your product?) ( may be it's happened because they don't like the colour of box) . You can't know it by qualitative researces. But in focus-group or during the long chat the interviewer can know it.

I don't like contradicting people, but Luke is mistaken in his answer. "Quantitative research" is research using facts and objective information. "Qualitative research" includes the bias, or opinions, of researchers. Sometimes a scientific problem is too complex or misunderstood to just use quantitative research, so scientists use qualitative research to help themselves better understand.

qualitative research is much depend on your analysis of the material , such like the statisitic, to give out your conclusion base on that. quantitative research is depend on your own thoughts about the material.