Quantitative research questions and research hypotheses are designed to accomplish different tasks:
Research questions
Explain the purpose of the research. In other words, what issue or problem is the research trying answer? In terms of quantitative research questions, the type of research question (i.e., descriptive, comparative and/or relationship) helps to explain the purpose of the research.
Research hypotheses
Explain the predictions being made (or otherwise) by the researcher based on specific hypothesis statements. These hypothesis statements set out what problem or issue the research is trying to answer, as well as their directionality, which help to explain the predictions being made (or otherwise) by the researcher.
If you choose to use research hypotheses, whether instead of research questions or in addition to them, these should be written differently to research questions. However, if you are using quantitative research questions, we have articles that can help you learn about the different types of quantitative research questions and how to structure quantitative research questions.