Ma'am & Madam

They are the same. It is a title used for women as an address. The first one is the short version of the the latter. Usually, more people use the first term sice it is more causal to say it. However, it is still depends on the environment and the people being addressed. If you are in a formal environment or in a wiring capacity, the second is usually used due to the formality. But in later instances the second one can be adopted.