Warning: The following contains spoilers for Demon Slayer and Dororo.
Demon Slayer and Dororo are two anime that appear to be cut from a similar cloth. Both take place in a historical Japan where demons run amok, and where the hero is tasked with killing the ones affecting human lives. They both question what makes someone human and star protagonists who are driven by loss. They deal with a number of similar themes, but what separates them is how these are handled.
For example, Tanjiro and Hyakkimaru both help others by killing the demons they come across, but they do so for different reasons. Tanjiro does it to find a way to make Nezuko human again, while Hyakkimaru wants to reclaim his stolen body. Between the two, it's obvious that Demon Slayer is more popular. However, Dororo might be a better choice for anime fans who are looking for something different.
Maturity
Demon Slayer has plenty of mature moments sprinkled throughout, and they're evident from Episode 1 when Tanjiro and the audience get a good long look at his slaughtered family. Moving forward, the series covers all kinds of gruesome acts, from humans being used as puppets to bloody on-screen death scenes. With Season 2 ongoing and set to cover the Entertainment District Arc, there will only be more adult themes making their way into the anime. However, as a shonen title, it has the ability to take breaks from the gory reality and spend entire episodes with the characters training and enjoying themselves in a safe environment.
In contrast, Dororo always has something sinister looming. Not only are demons wreaking havoc, but Japan is torn apart by warring factions and its citizens are living with the consequences. Characters like Jukai wander past battlefields and among armies of corpses in various states of decay. Others like Mio do anything to ensure that their loved ones have enough to eat every day, no matter the danger involved. Their respites are found in the briefest of moments, like Hyakkimaru feeling rain on his skin for the first time or finally learning what a flower smells like. These fleeting instances are all they can afford, as danger lurks behind every tree.
Family
One of Demon Slayer's biggest themes is the power of Tanjiro and Nezuko's familial bonds. It's her love for Tanjiro that keeps Nezuko from fully becoming a demon, and she doesn't attack humans because she sees them all as her family. Likewise, Tanjiro has committed himself to years of hardship, literally carrying her on his back, in hopes that he can make her human again. Their connection cannot be severed when it's challenged, and they make an incredible team in a fight. They're easily one of the best brother/sister dynamics in the current anime sphere.
Dororo also explores familial bonds but focuses more on the family Hyakkimaru has found rather than the one he was born into. He initially wants to find the family he was born into, but doesn't like what he finds. They're nothing like the picture of a family that Dororo paints for him. In fact, his father and brother want him dead. He does find people who fit his image of family, but not in his bloodline. Hyakkimaru calls the prosthetic expert who found him his mother because the man fits the role more than anyone else in his life. He may not have family in the traditional sense, especially after the season finale, but the one he does have is just as important.
Humanity
Dororo uses Hyakkimaru's lack of a body as a metaphor for humanity. With it, the anime connects being human with the body. People experience and participate in the world through their bodies. Those whose bodies prohibit them from doing so can feel less than human. With most of his own body stolen at birth, the only way Hyakkimaru can blend in is with a full body of prosthetics. However, even then, the way he perceives the world is different from most. He's lived his life outside of human society and is outraged upon learning just how much he was missing out on. With every body part returned, he literally becomes human.
Demon Slayer takes a much wider view of humanity, showing that even the demons who serve as villains are still human deep down. In this anime, being human is defined as caring for and wanting to be around others. Nezuko sets an example by retaining her love for people even when she's starving, but this seems to be true for every demon. With every demon that Tanjiro cuts down, the audience gets glimpses of who they were before their transformation. Often, they were people at the lowest points in their lives who were promised a better life if they became demons.
