Despite the common and growing use of and instruction on digital reading in schools, the ways in which reading comprehension may operate differently in paper and online environments are still underexplored. Using publicly available national datasets, we explore similarities and differences in how varied comprehension processes relate to each other in these spaces. Analyses using a Bayesian unidimensional graded response model found that paper-based reading performance involved hierarchical comprehension processes consistent with traditional theories of reading comprehension while digital hypermedia reading did not involve these same processes. This research provides usable knowledge for supporting researchers, and teachers in uncovering the unique educational benefits and challenges of online reading.