This study used phenomenography, a qualitative method, to investigate Taiwanese mathematics teachers' conceptions of school mathematics, school statistics, and their differences. To collect data, we interviewed five mathematics teachers by open questions. They also responded to statements drawn on mathematical/statistical conceptions and epistemological beliefs in the literature. We also conducted a survey of 22 mathematics teachers who responded to open-ended questions for comparing and justifying the findings from the interview data. We found that the characteristic features of the categories and dimensions of these teachers' conceptions were different from those in the relevant literature. All of the mathematics teachers' conceptions of school mathematics, school statistics, and their differences could be identified by these categories and dimensions as reflected by their characteristic features. We discuss our findings and their implications for further research and teacher education programs.