Architecture is what holds up the walls and the ceiling, including details like entries and windows.
Design is how the room is filled and decorated.
Of course, there are crossover elements, such as when a designer decides that exposed redwood beams need to be replaced with gothic arches. In such a case, it takes an architect to determine a safe way in which that ceiling can be redone. The designer is interested in "the look." The architect is interested in making sure the ceiling doesn't collapse.
On the inverse, an architect has esthetic choices as well. If he wants "cathederal ceilings" and lofty staircases, he has only do design the structure in such a way that it, too, does not collapse.
The course work may have some similarities, but, an architect has more knowledge of physics and engineering principles while the designer would have more detailed knowlege of color theory, fabrics and such.