Impossible to tell unless we know what specific courses you're talking about. It should all be explained on the course web pages, really.
Development Management will focus more on the technical/logistical/administrative side of things; stuff that you need to know for a career 'in the field'. DevStud and International Development, depending on where you go, are likely to be more academic and more critical of the (several, incredibly problematic) assumptions behind the idea of 'development', and do an excellent job of bursting the bubbles of starry-eyed undergrads who want to swoop into Mozambique and 'save' people. Highly recommended.