kcal is actually 1000 calories.
However, when most people talk about "calories" they mean kcal (kilocalories).
1 kilocalorie is the energy required to heat 1 cubic centimeter of water by 1 degree. (I think...)
But for non-scientific purposes, ie dieting purposes kcal and calories are the same thing!
kj are kilojoules... which is a different measure, and I think Australians measure kilojoules rather than calories

But both are usually available on nutritional information.