What are some differences between "The Celebrated Jumping Frog of Calaveras County" and The Adventures of Huckleberry Finn?
One huge difference is in the narrator. In "The Celebrated Jumping Frog of Calaveras County," we have a first-person narrator, but it is really a 2nd-hand 1st-person narrator, one or two people removed. It is a very strange set-up. Twain, who is telling the story, is actually telling it in the words of other people. So, it isn't a direct tale, more of a legend or tall-tale sort of telling. Huck Finn on the other hand, is told in the first-person perspective from just one kid's perspective; there is no second-hand or third-hand passing down of lore. So, the narrators are different in that sense.
Other differences are a bit simpler and more obvious; one is a short story, one is an entire novel. One centers around just one guy and his propensity for gambling, and the other centers around the endearing friendship between a boy and a runaway slave. Jumping Frog is more of a singular satire of one particular situation, whereas Huck Finn is a huge collection of tiny stories and satires all stitched together as a quilt of the American experience. In Jumping Frog, the main character is a bit of a rascal, whereas in Huck Finn, the side characters are rascals. There is less of a moral point to Jumping Frog than there is in Huck Finn; Huck Finn is replete with little morals and lessons throughout.
I hope that those thoughts help to get you started; good luck!