Let's just say Darker Than Black is much grittier and darker, and there are nothing assumed. It's also more intelligent and you can't find any over used cliche at all. If Witch Hunter Robin was an excellent show for you, then Darker than Black will be a superior show for you.
Both shows focus on the slow unravaling of a mystery and conspracy through police work and investigation, with small bits of action in between. Both have a case of interesting characters, great music, and high production values.
People with mysterious supernatural abilities join secret organizations designed to watch/control other people with similar abilities
Similar premise to both shows, superpowered people in a quasi-future society, both centered around a character with above average powers that seem conflicted. Both have elements of mystery, Darker than BLACK just feels a little more hardcore.
They are both similar in that they have a dark and ominous overtone throughout each anime, giving them a sense of realism and making the characters seem as thought they could live in a darker more fantastic world much like our own. Also both anime are based around characters that deal with supernatural powers or they themselves have supernatural powers.
Both anime are about peaple with supernatural powers and about organizations trying to control/eliminate such peaple. They also have somwhat more subtle character development than usual "from powerless idiot to superhero" seen so often in more common anime.
Very similar themes and both protagonists face the same kind of conflict about what they are. Shadow organizations, a slow start, a quite a few stand-alone episodes make them even more similar.
They both involve super-powered individuals in a near-future setting with some sci-fi elements, powerful shadowy organizations and stuff. The factual, thematic similarities aside, if you're done watching one and looking for a similar show, you should check out the other
Both revolve around a small group of people with certain abilities and follow a "case of the week" sort of pace until the end where they both break into their main story arcs dealing with the mysterious pasts of the protagonists.
Both shows are about worlds in which a small percentage of humanity have magical-type powers, and in both worlds, there are shadowy, secretive organisations trying to understad, control and exploit those powers. On the ground, these efforts involve small, elite teams who, as they go about their business, learn more than they ever wanted to and more than they should have about what really goes on behind the scenes. The two shows also share dark colour palettes and dour male leads.
WHR keeps a narrower focus and thus does more to develop and reveal its characters, who generally are more realistic than in KnK. The
Witch Hunter Robin and Darker Than Black both focus on organizations that deal with those who have supernatural powers, one being witches and the other "Contractors." The episodes run in a similar "monster of the week" fashion while developing the characters and story into something bigger and better later on. If you are a fan of either show, I would highly recommend the other.
Both are about people with special abilities. Dark atmosphere! Keeps you on the edge of your seat. A lot of plot twists! Not to scary, but not a children's show. I really enjoyed both of these that I am alway rewatching them and seeing things I missed the first time around!