Kneidlach and matzoh balls are the same thing -- the balls found in matzoh ball soup made of matzoh, egg and schmaltz or oil. Kreplach are dumplings stuffed with meat, cheese, potato or fruit compote.
Kneidlach are dumplings that are usually stuffed with beef. Kreplach is like a ravioli that is fried. Matzah balls are a light fluffly round dumpling. All are served in soups.
Kneidlach is the same as matzah balls that are golden flour dumplings in chicken soup Kreplach, stuffed dumplings with meat, potato, cheese, and any other stuffing you prefer.
Kneidlach is another word for matzah balls which are commonly found swimming in chicken soup. Kreplach, are dumplings always stuffed the stuffing will vary usually with meat, potato etc.
