Data preparation or pre processing is an important issue for both data warehouse and data mining. In data mining pre-processing means preparing data, it is the one of the important and compulsory task. Before applying the data mining techniques like association, classification or clustering noisy and outliers should be removed. In this paper the authors are trying to find similarities and differences between noisy data and outliers. Actually most of the data mining users are thing that these two are same but lots of differences are there.