Berman has it right, but the main question you need to ask yourself is do you want the engine panels closed or open? Based on photos of the plane you are building this will answer the question which kit is the best for you, the main issue with the Eduard D.VII is that the upper engine cowls are molded closed as part of the fuselage half, and there is no interior engine compartment detail and only a rough approximation of a slightly small Mercedes engine. For the BMW engine they tell you to use the same engine but give a different carb & intake pipes for the BMW. The Roden kit on the other hand, while slightly fiddly to assemble is the kit that you want if you are doing an aircraft with the upper cowls removed, as were many of the early D.VII's in the summer of 1918. The Roden kit gives you two different engines, a nicely detailed Mercedes and BMW. They also give you all of the inner framework and separate side panels.
Dave