The History, Theory & Urbanism concentration in the Architecture major is for students who want to graduate with an Architecture major but with specific coursework in urbanism. In sophomore year, students intended to major in Architecture are required to take all the prerequisite courses ARCH 1500, 2000 and 2800.
Urban Studies major is for students who are interested in studying the built environment without becoming an architect. There is no prerequisite courses for the major, and you can convert many courses taken outside of the department to count towards the major. So, with less required courses, you will be able to fully engage with the Urban Labs in your junior year, and have more liberty to take elective courses.