Very interesting question. Of course, both stories contain two characters of whom at least one hates the other and wants to gain vengeance. Both stories end in at least one death and both contain grimly ironic humour.
But these stories are more different than the same. Let us think about the point of view. "The Interlopers" uses omniscient point of view whereas "The Cask of Amontillado" famously uses the first person unreliable narrator to show us the demented mind of Montresor. "The Interlopers" depicts a feud between two families going back through centuries but which is actually halted due to the shared experiences of the two main characters. "The Cask of Amontillado" is about a secret feud, of which the justification is extremely doubtful. Lastly, tragically but ironically, the two characters in "The Interlopers" both die in a tragic twist of fate. "The Cask of Amontillado" ends with the death of the poor unsuspecting Fortunato at the hands of the lunatic Montresor.
Both stories deal with revenge yet have radically different perspectives on it. For Montresor, revenge is what consumes him against a supposed insult. He plots a criminal way of ensuring that he is able to dispense revenge himself in a horrendous fashion. In "The Interlopers", both characters begin consumed by revenge, but actually spending time with each other shows them each other's humanity and ends the feud between them. However, ironically, in spite of this, they die together at the hands of wild wolves.