The climax is the most exciting or intense part of the story. "With a loud yell, I threw open the lantern and leaped into the room. He screamed once - once only." This is the most intense because he dismembered the body.
The falling action is the part after the climax. "When I finished, someone knocked at the street door. I went down to open it with a light heart. What had I to fear?" This is the falling action because it is calmer than before.
The resolution is the ending of the story. "Villains!" I screamed. "Enough! I admit the deed! Tear up the planks! Here, here! It is the beating of his hideous heart!" This is the resolution because it is the end and following the climax.