Curriculum mapping is a comparability method that facilitates comparisons of content within multiple settings (usually multiple jurisdictions or specifications) and enables claims to be made about those curriculums/jurisdictions. Although curriculum maps have been published, there is little academic literature about the process of constructing and using them. Our study extends the literature by considering the different types of comparisons that can be made from curriculum maps: content coverage, placement, depth, and breadth. We also consider how these comparisons are affected by structural differences in the curricula or using a subset of the content. We use our mapping of mathematics in the US Common Core State Standards (CCSS) and the national curriculum in England to explore this. The CCSS for mathematical practice are common to all grades; we mapped these standards against the content for individual years in the national curriculum. The CCSS for mathematical content are set out by grade; we mapped a subset of this content to the national curriculum. Our mapping shows that it is possible to map curricula and make meaningful comparisons despite structural differences and content limitations. However, this affected the types of comparisons that we could carry out and the claims that we could make.