from what i understand dcs:ww2 includes p-51,fw-190 and bf-109.ww2 is a package of all selected ww2 era planes.they have been slowly coming out with planes.you can also buy the planes separately.
(i think that p-51 was made by ED but the ww2 will improve something about it)
p-51 and fw-190 are running on the same rendering engine as all of dcs modules.