Indicate whether the observational study used is cross-sectional, retrospective or prospective: Researchers from the National Institute of Health want to determine the current rates of smoking among adult males and adult females. They conduct a survey of 500 adults of each gender.

The major difference is that a histogram is only used to plot the frequency of score occurrences in a continuous data set that has been divided into classes, called bins.  bar charts, on the other hand, can be used for a great deal of other types ofvariables  including  ordinal  andnominal  data sets.