As nouns the difference between litter and nitter
is that
litter is (countable) a platform mounted on two shafts, or a more elaborate construction, designed to be carried by two (or more) people to transport one (in luxury models sometimes more) third person(s) or (occasionally in the elaborate version) a cargo, such as a religious idol while
nitter is (zoology) a louse that deposits nits on horses.
As a verb litter
is to drop or throw trash without properly disposing of it (as discarding in public areas rather than trash receptacles).