Histograms and bar charts are different in several ways, but a major distinction is that the bars in histograms represent ranges of data, while the bars in bar charts represent categories. For example, a histogram might plot the percentage of visitors that went to a museum in 10-, 20- or 30-minute ranges. A bar chart might plot the number of visitors per category, such as the different museum exhibits.
In bar charts, the bars or categories can be rearranged in any way, alphabetically or by size. In histograms, the bars represent the percentage or distribution of values per range of grouped data. Because of the continuity of the information presented, it is not logical to rearrange the bars in histograms.
Another distinction is that histograms don't have spaces in between the bars unless a range has zero value. Bar charts can have spaces in between since each one is independent of the other. In addition, the bars of bar charts are typically drawn to have the same width, but this is not so in histograms. Each bar in histograms actually represents an area equivalent to the percentage of the range value. The width doesn't matter so long as the total area of the histogram equals 100 percent.