This is not an easy question to answer, especially since there will be exceptions to any definition given. The differences are partly determined by the subject of study as well as the methods of study. In general, Theological Studies focuses on the critical study of Christianity from a perspective that it is broadly informed by the Christian tradition. Many enroll in Theological Studies programs a preparation for Christian ministry, though not everyone in such a program will pursue ministry. Religious Studies typically studies a wide range of religions from more an external perspective. For example, if you are looking to delve deeply into the texts of early Buddhism, the contemporary practices of Muslims, or the effect of Christian evangelicalism on voting patterns in Canada, you will find that a Religious Studies program will be a better fit.