The research design is more like the general plan of your research. But your research methodology includes your population (and why you intend to research these people), sample size (and how you came up with the number), explaining your method as in what type of analyses you intend to use, your tools if you are using any and then the procedure. The research design now is a bit more general as said before and it includes information like what is the purpose of your study and how you will answer your Research Question.

Research design is a method applied for analyzing collected data or details. They are techniques to be implemented for collecting and analyzing research.

Research methodology is the specific procedures or techniques used to identify, select, process, and analyze information/data about a topic. In a research paper, the research methodology section allows the reader to critically evaluate a study's overall validity and reliability. There are two main research methodologies: quantitative and qualitative. A third methodology, a combination of the two, is gaining acceptance as a way to improve and substantiate research findings. "Thematic Analysis"?.

Research Design: The overall plan of the research, determining the type of study, sample selection, data collection, and analysis methods. It ensures the research problem is addressed effectively.

Research Methodology: The specific methods and techniques used, including data collection and analysis procedures, tools, and instruments. It explains how the research will be conducted.

Research design focuses on "what" and "why," while research methodology focuses on "how."

I think research methodology is broader than described in the previous answers. In particular, it refers to general aspects of the overall project, such as the use of qualitative or quantitative methods, whether the goals are descriptive, exploratory, or explanatory, so on.

In contrast, I research design specifies how you will use your specific methods to collect and analyze your data.

I think research design determines what needs to be done, while research methodology determines how it will be done.