In this open access article in the Canadian Journal of Surgery, the authors explain the difference between research questions, hypotheses, and objectives and how each guides your research.
The research question is central to the study—the hypothesis and objective are derived from it. The research question is what the study is designed to answer. It should be something novel and of interest generally. The question should be quite specific about the subjects and variables of study. It should also be something that it is feasible to answer and can ethically be researched.
You need an in-depth knowledge of the topic you are interested in before you can write a good research question. Good research questions address the boundary between the known and unknown. Until you find out exactly what is known you will not know where this boundary is.
The research hypothesis is based on the research question and specifies the main elements of the study, including the participants, the comparisons being made, and the variables being studied. Not all studies have hypotheses—for example descriptive studies may not.
The research objective defines what the study will accomplish and how it will answer the research question in terms of specific outcomes.
Check out the article for more detail here.
Farrugia, P., Petrisor, B. A., Farrokhyar, F., & Bhandari, M. (2010). Research questions, hypotheses and objectives. Canadian Journal of Surgery, 53(4), 278-281. Retrieved from http://canjsurg.ca/wp-content/uploads/2013/12/53-4-278.pdf