Huck Finn HELP!

i have to figure out what the differnces when huck and jim set up the river and the differnces of when they set down the river. i'm thinking thats its talking about the differnces between the North and South... but i have no idea where to start!!

help would be appericated ! thanks

Memory a little hazy but I think the constrast would be that by the ned of the second journey Huck has a sense that slavery is wrong and that Jim has a life that is worth saving and respecting as a man. Hope this helps. Rich