"The Tell-Tale Heart" is a first-person narrative by an unreliable narrator of questionable sanity. He is constantly attempting to reassure his audience that he is not mad, yet he describes his behavior in a way that seems to suggest that he is. He has murdered the old man with whom he lived and can give no explanation except his dislike of the old man's pale blue eye, which looks like that of a vulture. The murder is carefully planned and executed, and the narrator hides the corpse beneath the floorboards. He is confident of having escaped detection, but as soon as the police arrives, he believes that he hears the old man's heartbeat and gives himself away immediately.
"The Black Cat" also has a first-person unreliable narrator, who may be insane, though he is less nervous and erratic than the narrator of "The Tell-Tale Heart." He also commits murder and bricks up the victim, his wife, in the wall of his house. Although this was an unpremeditated, almost accidental crime, the narrator is able to hide it successfully at first. He is then betrayed, as in "The Tell-Tale Heart," by a sound from within the tomb.
Structurally, the stories are very similar: a first-person narrator, who may be mad, commits murder and hides the corpse. He then hears a sound from the hiding place, which gives away his crime. The principal differences are the lack of intention to commit murder in "The Black Cat" and the role of alcoholism in that story. "The Black Cat" is also a more complex story, and it is related in a less agitated manner.