This paper addresses one of the major confusions in the study and practice of problem-based learning today, namely the use of the term "problem-based learning" to refer to both the small-group tutorial method pioneered by McMaster University and Maastricht University in medical education, and the problem-oriented project-work method developed in Denmark at the universities of Roskilde and Aalborg, which has gained prominence in recent years in the field of engineering education. This paper offers a comparison of the models using a thematic analysis of key elements of PBL, namely the nature of problems, the role of teachers, the nature of the educational process, and the underlying principles of the method, to conclude on a discussion of the causes of the confusion taking place today, and its potential ramifications for the study and practice of PBL in the future.